First of all, I think VVVVVV is an awesome game, but you should not list it in a budget thread. It's heavily overpriced for the 2 hours it lasts, imho. I still love the game and have it on my 3DS and it looks and plays awesome, but I still think this game should be 5 bucks max.
If you buy a 3DS and have not much more money to spare I would get Pushmo, Crashmo and Mutant Mudds off the eShop. If you want something to stuff into your 3DS slot so that no dust gets in I would go for Resident Evil Revelations. I have seen it on amazon.com for sub 20$ which is also very good value. Or stuff Dragon Quest IX in there if you haven't played it already.
Ongoing bet with think-man: He wins if MH4 releases in any shape or form on PSV in 2013, I win if it doesn't.