I'd rather buy one of these: http://en.wikipedia.org/wiki/Generation_NEX
While the NEX sounds good in theory, it's not as good as the original hardware.
The NEX is a clone system using an all-in-one processor that does everything that the original NES hardware did. The chip is cheap and contains flaws which result in inaccuracies such as the wrong sound pitch, sprite flickering, glitches and general incompatibility with games that used more advanced mappers to push the hardware.
Famiclones are nothing new; they've been around for almost as long as the Famicom itself. Early clones were complete copies but later ones reduced the entire thing to a single tiny tiny PCB.
The NEX is an overpriced Famiclone. The only reason it got more attention than others is because the makers actually advertised it.
If you want the NES experience on the cheap and don't mind the flaws, I sugges the Yobo FC Game Console instead of the NEX. You can find them new for $20, they're as small as the Gamecube and you can use real NES controllers if you have them.
Basically, don't get a NEX.