I am thinking of making one of those "find difference" games that compares two images for five differences to find, but I am having trouble finding decent stock photography to modify. I really like the ones on sites like shutterstock.com and iStockphoto.com, but am I reading the licensing terms correctly? There is a standard and extended license, but based on the restrictions, I would need an extended license because the Flash and free mobile app versions of my game could easily get more than 500k hits, so it would cost over a hundred dollars per photo?! Is that right?

I am willing to pay for royalty free photos, but I need over a hundred and spending more than $10,000 at this time is out of the question. Stock.xchng has a sketchy license agreement for the kind of game I am making. Any ideas?

If they are royalty free, then you need not pay more than the base charge...? Right? Or are there special terms for bigger hits?

I don't recall particularly reading their licensing terms, but they're all pretty much the same.

You're probably interpreting the terms right. Usually stock photo websites are meant for:

1. Artists looking for reference images (a few or a lot of them) to boost their imagination or get precise details. They keep the image for themselves but make (i.e.) a 3D model out of it. Usually they go for a standard license. Cheap.
   
2. Someone looking for a photo for personal usage. Standard license. Cheap.
   
3. Someone looking for a photo to copy paste on an Street Ad, TV Show, etc as a background or as the main image. They go extended license. But paying a hundred dollars for an that possibly costs thousands (in some cases millions) is really cheap.
   

Often you see someone looking for hundreds of photos, which are often artists, going for standard license.
You rarely see someone needing to buy hundreds of photos with the extended license because they use the stock photo directly; that's why it's so expensive for you; you're basically out of their business model.

You may want to try to contact them for a custom plan, may be in bulk or revenue share; but don't get your hopes up. These sites make their living by selling stock photos; they're not gonna like an application distributing such a high ammount of photos to everyone for free; unless you cover the licensing well enough.

My advise, take a photography course (or learn by yourself; start by knowing what the ISO is, google "colour theory", "camera exposure") This site is meant for films but contains a lot of useful information about taking correct shots. And buy a good camera if possible. It's not just the megapixels, but rather the quality & size of the lenses and the JPEG compression (if it takes RAW pictures, then better) which is more important.
Take most of the photos yourself and buy a few in stock, it's cheaper and a lot more fun. There's no reason you can't came up with good quality photos. You'll probably get what you're looking for more easily.

Edit: Have you visited 3D.sk? (and their sister sites for environment photos) They're used to the gaming industry so you'll probably find friendlier licensing terms for your needs.
Edit2: Beware that Env. Artist's TOS your game might fall into terms of Prohibited Use (point 5 "(...) or is otherwise made available in a manner such that a person can extract or access or reproduce the Content as an electronic file") depending on how your game is implemented (i.e. flash content obfuscation, there's an article in GD.Net about that) I suggest you first contact, they'll know better to answer your particular case.

Why don't you just take a couple of pictures yourself? Should be fun to do too and your phone will be perfect for making fotos to display on a mobile device.

Some places you might consider going too and most should have nearby:

1, Farm land, cattle or flower fields have great amounts of detail to hide those changes you make.
2, Industrial, in particular old industrial buildings have lots of detail, fixing a piece of glass or moving some rust stain around will be hard to spot.
3, Inside shops, shops are often very "busy"decorated making a excellent place to take pictures for this project.
4, Nature, forests, hills, mountains or even just plain old regular parks.

I would add also shopping centres, suburban areas and trains

PhotoDune has some cheaper prices -- I've yet to see an "extended licence" with a cost of over $30 in their collection -- they also base their prices on the size of the images in question, and whilst you would need larger images for backgrounds/locations you could certainly use smaller images for items within a scene. As a relatively new site they currently have a smaller collection than you might be able to find elsewhere however. I haven't visited shutterstock or the other sites you mentioned -- but have you checked to see if they offer lower resolution images for a lower price?

I'm sure there are other places with royalty free images available at cheaper prices if you're willing to do some searching.


As another alternative, you could also try looking for images that have been released to the public domain or which are provided under a suitable Creative Commons licence. Most of the Hubble Telescope Images and other NASA Images are released into the public domain (unless they state otherwise) for example, and many image-hosting/sharing sites such as Flikr and DeviantArt now offer specific categories or search options to find content with Creative Commons licencing.


If those are of no use you might try taking your own pictures as some people have suggested above -- Matias Goldberg appears to have given some excellent advice should you wish to pursue that option. I'll just add to what has already been said that you should be careful about taking/using photos of trademarked names/images or recognisable landmarks, as you may not be able to use these without a release -- that being said, there are a great many things and places you can get some great pictures of without this ever having to be a problem, it's just something to keep in mind before running off to photograph the Eiffel Tower or other famous landmarks.


Hope that helps!