Nintendo's DRM nonsense largely keeps me away.
It doesn't get bought if it's multiplatform or appears to stand a good chance of receiving a retail release eventually (DuckTales Remastered, Wii Sports Club, and both NES Remix titles spring to mind for some recent examples where waiting paid off). The only exceptions to date have been Mega Man 9 & 10 on the Wii that I bought on Nintendo's console despite 360/PS3 versions being available.
That leaves me with the odd Nintendo exclusive and the Virtual Console. I do buy some of my favorites on the VC for the convenience that I own in original form, but between Nintendo's restrictions and VC prices that I think are about twice what they should be (I bet the loss of revenue from each sale with a 50% cut across the board would more than be made up for in volume), I'm very deliberate there with what I purchase.