Or for free you can root your android device, link a PS3 controller, and play all the emulators your want via micro-HDMI to your TV. Yes it's free and it works perfectly. You can also pay a few bucks for more flashy emulators if you want. I applaud them for trying to do something like this, but it's not like you are playing NES games, you are playing "iCade" games.
I also have my new Nexus 7 linked up like this (minues the HDMI, but the screen is big enough), it even plays PS1 games perfectly.