I think that this a great idea. 2d games (especially with the explosion of mobile games) will always need sprite sheets. Just Google for sprite sheets and you won’t find very much on offer. I think there were two main packs for sale last time I looked .. Ari Feldman’s Sprite Pack and .. umm .. some other sprite pack. Not even sure that Ari’s stuff is still available.
Will buyers understand it? Well, the ones making games should.
Sprite sheets are the most common way of ‘doing’ 2d games and probably always will be… especially now that most 2d engines are based on 3d planes and that the 2d animation code is a case of switching UV positions around per frame.
Most indie game engines support sprite sheets, too (Unity Indie (using SpriteManager2), Blitz, FPSC , Dark Basic etc.). If you really wanted to cover all bases, offer the sprites as a folder full of images as well as a single sheet. Then they’re ready for anything!
Having sprite sheets set up in a 3d program would be great, but it’s more specific to project requirements I’d say. Right now, I’m working on a 2d game in Unity that doesn’t require anything other than 2d planes and all of the graphics are coming to me as separate images which I’m converting into sprite sheets.
I think that sprite sheets on here are a great idea, but the main block I see for purchasing would be the license. Your biggest market would probably be mobile or indie devs, which means they will be looking to try and make something out their efforts albeit a few bucks in selling upgrades or a few bucks in selling ad-free versions within ad-funded versions.
Knowing where the line is for ‘making money from, thus requiring an extended licence’ and ‘making money indirectly from so that a standard license is OK’ is a tough call. I know how much work it is to make graphics and I am not arguing the price (since $140 is great for a set of game graphics) but I know that when it comes to stock graphics, it’s a different ball game.
Hope my babble helps 