When I had to get passport photos for my Italian Visa a few years ago I wanted to find the place with the cheapest price. The lowest I found was $13 and even then I knew I might not be happy with the picture they would have taken and passports don't expire for 10 years. My current passport photo was taken shortly after I shaved my head for St. Baldrick's and it looks nothing like me now. I still have a few years left until it expires.
I found an app called Passport Booth (available for iPhones) that I used for my photos. It was really easy and free! The app does have ads but they aren't annoying. I tried to find a better app but some charge you to export the photo in color. This was the best one I could find!
U.S. PASSPORT PHOTO RULES
Since you are doing this yourself you need to make sure you follow the rules so your photo gets accepted. I also heard that your hair needs to be behind your ears so do that just in case. Here is an excerpt directly from the U.S. Embassy website on the requirements:
Photos must be 2″x2″ in size with a background that is uniform, plain and white, and free of shadows.
If you are applying for a U.S. Passport, you must provide one (1) photo. Your passport photo must be:
In color
Printed on photo quality paper 2 x 2 inches (51 x 51 mm) in size
Sized such that the head is between 1 inch and 1 3/8 inches (between 25 and 35 mm) from the bottom of the chin to the top of the head. View the Photo Composition Template for more size requirement details.
Taken within the last 6 months to reflect your current appearance
Taken in front of a plain white or off-white background
Taken in full-face view directly facing the camera
With a neutral facial expression and both eyes open
Taken in clothing that you normally wear on a daily basis:
Uniforms should not be worn in your photo, except religious clothing that is worn daily.
Do not wear a hat or head covering that obscures the hair or hairline, unless worn daily for a religious purpose. Your full face must be visible, and the head covering must not cast any shadows on your face.
Headphones, wireless hands-free devices or similar items are not acceptable in your photo.
If you normally wear a hearing device or similar articles, they may be worn for your photo.
Glasses are not acceptable in your photo. If you cannot remove your glasses for medical reasons, please include a signed note from your doctor with your application. Glare on glasses is not acceptable in your photo.
Glare can be avoided with a slight downward tilt of the glasses or by removing the glasses or by turning off the camera flash.
HOW TO USE THE APP
Here is an image from the app that gives simple instructions:
When you take the photo go to the next page. It will prompt you to email and/or save the prints. You can also buy prints directly from the app but this might take a while to arrive and is not the cheapest option. When you save or email it you can select two photos, six, or just one one a 4" by 6" sheet. I recommend you print the sheet with 6 in case you mess up cutting them.
WHERE TO PRINT
You can email the photos to yourself and upload it to CVS Photo and pick it up the same day. The price is 33 cents. You can also print it at Walmart Photo for 25 cents to get it in under one hour which might be the cheapest and fastest place. If you have a Costco membership it is 17 cents there. I printed mine at CVS and had no problem. My Visa was accepted and I did not look like a potato! Since they won't cut your photos there you can carefully cut them with scissors, an X-ACTO knife and cutting mat or go somewhere they have a paper cutter like Fedex or Office Depot.