Hi C., I'm going to get my 7 year old one for Christmas too. I have shopped around a bit and was told this:
Get one that has a reasonable size memory card so you can transfer pics to the walmart machine and also so they can take lots of pictures.
Also, make sure it can hook up to your computer so you can edit before you go to walmart and save you time and money. I have found the $20-$30 version at Wal-Mart in the camera section pretty worthwhile and comes in different colors too.
Just an FYI- Lithium batteries cost more but you get longer more quality use for the buck. Or try Duracell - they have a longer shelf life as well as a quality energy output. Be sure they turn the camera off after using to save on battery life.
Have fun!