I have let my roommates kids play my DS a ton. One is 4 and the other is 5. Luckily they took great care of it and it is relatively no worse for the wear. Just some greasy fingerprints now and then, but those clean up.
Hey, Gare. Where are you in Radiant Historia? I was thinking earlier of asking you for a save file, since mine is now non-functional.
I got mine online, I think, and for less than 10 bucks. Plus, it's a Hori one. People say that's the best one, and after 2-3 years of using my DS, it seems those people were right.
Still, between scratched DS screens and losing 16 bucks, I'd probably pick the latter. SCRATCHED SCREENS DRIVE ME UP THE WALL.
I keep my PS3 and 360 Slim vertical too. I pretty much have to with the 360 since in horizontal position it has a bloody great exhaust fan on the top that gets obstructed by the above shelf in the TV unit. :/