The Nintendo NES Classic has proven to be more popular then anyone planned. Months after the release the NES Classic is still extremely rare. The other down side is that it only 30 games. You can wait around to buy one of these, or you can build your own (which some people might consider better). You just need a Raspberry Pi B+ and some technical knowledge. Best of all you can even build your own NES case out of Lego. WayGroovy has done just that. This MOC is based on the work by Chris McVeigh. With a few modifications WayGroovy was able to fit the whole thing in an amazingly small package.
The best part is that they documented the process, so you can build one yourself. Check out the Lego NES Pi Case here: http://imgur.com/a/8EeyD