This site has a fair amount of information on printing photos from your iPad, but the most cost effective way is still sending them out to a photo lad. At less than 10 cents a print it can be an eighth the cost of printing them yourself. The only tricky part is sending the photos and actually putting in the order. You can save the most money by having the prints mailed to you, but if time is an issue you can pick them up at a local retailer (Walgreens, Walmart, etc). As always the article gives you various options and instructions.
The Shoe-leather and Gadget Method
The PNY ZoomIt Flash Memory Reader for the iPhone and iPod Touch, unlike the Apple Camera Kit, will allow you to copy Photos from your iOS device back to a SD Card. Once on the card you can treat it like any other from a digital camera. Go to your local pharmacy, Target, Walmart, where ever you can get photos made. Give them your card and you can get prints made. They may even have a kiosk where you can insert the card and put in the order right there. No fuss, no muss. Except for the $50 for the special gadget. This works best if you local options are limited and you can't wait for the mail.
The biggest obstacle to ordering photos over the internet is Apple's web browser and your web store's ordering process. Safari (the default web browser) doesn't support file uploads and Flash, so we need work arounds or an purpose built app for success. Below are one that worked for me.
Photographs are available for local pickup at Walgreens through either the Walgreens app for as an option from the Snapfish (see below) website. Prices for 4x6 prints are 19 cents (pickup) and 12 cents (mail). 8x10 prints are $2.99 (pickup and mail). Free offers and specials are frequent. Pickup orders are paid for at the store, so no credit card info required.
The Walgreens app recently made print orders available.
Before a recent update you used the app to upload your photos then Safari to make your print order. Now you can put the order in directly through the app. I think Safari worked slightly better, but now you have a choice. If the app starts acting funny try logging into the Walgreens website through Safari.
Not as big as they once were, Ritz Camera is still a local pickup option from me. The RitzPix app (see above) looks like a third party rebrand that is used for several regional camera stores. I bet they all work the same. The app works best with images in your Camera Roll. For some reason images in other albums can only be uploaded one at a time. That's a deal breaker for me. On the iPad most of the best images are probably going to be imported through the Apple Camera Kit, so won't be in the Camera Roll. I'm not going to upload a couple hundred images one by one. Also when you do put in a order be careful of the aspect ratio of your images. With borderless prints and a wide aspect ratio it is possible to be loss resolution, bad quality prints.
I had big hopes for Kodak, but I encountered deal breaker pretty early on... you upload all images one photo at a time. This could take forever for me. I don't care how much or how good the photos are. I don't have the patience to find out. When/if the app is updated I'll give them a try. For now it is a no go.
Update (9-25-2012): Kodak is dead.
No complaints about uploading photos from the Shutterfly app, but if you want prints you'll need to order them through the Shutterfly website. That's where I ran into some problems. Target, Walgreens, and CVS are listed as local pickup options. But even if you select a store, your order will always be for mail delivery on the iPad and on the Mac. This is a shame since that would have made Target and CVS options on the iPad. Prices for 4x6 prints are 15 cents (with a prepaid plan they are 9 cents). 8x10s are $3.99. Those are all mail order prices since local pickup isn't an option when using the iPad or a Mac.
No love for the iPad, but the iPhone app for Snapfish works kinda... at first I thought that the app only uploaded photos one at a time, but then I realized that it was. The app is missing a selection indicator, and a more obvious UI for the upload queue. But it is there and works. It is just slow. Like many other services once you upload your images you need to use the Snapfish website to put in a print order. Here is where things get better.
On the Snapfish site you will find an option to import your Flickr and Facebook photos. While Snapfish's app is ok, I prefer the app I use to access Flickr, Flickr Studio. Uploading from that is pretty easy (it has a learning curve) and quick (see below). Now getting images into Snapfish is no problem and ordering prints from the Snapfish site works well. Prices are 9 cents for a 4x6 print (mail), and 19 cents at Walmart (it is 13 cents if you want to do the shoe-leather method, see above).
Update (9-25-2012): Today the Snapfish app was updated to allow ordering prints without using the website. Using the app is much faster than the website. Walmart, Walgreens, and DuaneReade are the supported photo processors.
I like the Flickr web site, but it is pretty much unusable from my iPad's web browser. I knew you could order prints from the site, but had little hope of it working and up until very recently I was right. But now you can order prints from Flickr website (the option is in Sets that you create or under Actions from your Photos. When you select the action you are directed to login to Snapfish, your photos are then transferred and you can begin the order process. Not bad at all. As a side note, try out Flickr Studio, $4.99 as a replacement for the website. For most other things I like the app better than the website. You will need an app to upload images to Flickr.
Mpix Tap To Print Brings Metallic Prints to iOS
Got an email from NAPP (National Association of Photoshop Professionals) advertising Mpix, an app-based photo print service. In this very attractive app, the first step is to add some photos from your camera roll. Very easy no problems with selecting multiple images. Each photo can be assigned different options (paper size, paper type, B&W, rotation, and quantity) before they are add to your cart. Don't worry about mistakes, just tap on the item to adjust. Tap Checkout, setup your payment account, and get your prints in 3-7 days.
Prints are available in a variety of sizes; standard photos (4x6 and 5x7), square (4x4), large (8x10), and panoramic (15x5). Prices are pretty good either within a few cents of equivalent services or cheaper, plus Mpix offers a larger variety of options and sizes.
The standard paper finish is called E-Surface. It's a matte coating so don't expect the standard glossies from the drug store. It is described as a professional paper which boasts, rich sharp color that won't fade. The paper itself is Kodak Endura. Quality wise the prints are very nice, but some people like gloss.
The second print type is Metallic. It is described as having a unique pearlescent surface that offers highly saturated colors, ultra-bright backgrounds. I've actually ordered this kind of print before from Adoramapix. Metallic prints are very dramatic with color that can really pop.
I along with my order, I included a metallic 15x5 panoramic print for about $5. The image was a double rainbow shot of the Grand Canyon I printed at Adoramapix (same Metallic paper). The only difference between the two prints are size and price. Mpix was 15x5 ($4.99), and Adoramapix was 20x20 ($14.95). I had to manually trim the 20x20 print--big waste for a panorama. I love panoramas, so I'll be using Mpix again.
Mpix actually has more interesting/fun photo products (Accordion folios, Keepsake boxes, Playing Cards, and more). Unfortunately they ware unavailable from the app and the website requires Flash to order them. I would like to see the app updated to add some of these fun products, but I'm not holding my breath. I do see however that the website offers Lustre Coating as an option. It would surprise me to see that popup as an option in a future update.