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.
The main game is only two to three hours, but the additional 18 levels (two of which are longer than the main game: I actually like 333333 better than the main game too) dramatically boost playtime. I'd say you can get an easy 15-20 hours out of it.
P.S. F*** The Tower of Power.