Nobody sells them. Suff is simply a few guys who mod 360 controllers and use aftermarket shells, sticks etc. All things you can do yourself if you can solider... it's very easy. (i mod controllers)
If you want something that replicates buttons and has great reviews check out Razer's new Sabertooth controller. Mine is still on backorder.
Slam brings up a good point though. Best estimates are saying the next gen Xbox will be released for holiday 2013/early 2014. It's far enough that i'm not too bothered... but to each his own.