Nuklear I reckon your chances are low to non-existent now, purely because you're way too late to market.....but if you can differentiate yourself you might have a chance, at least in Australia.
How? Well every groupon clone here seems to sell total runoff or seconds junk. I mean space-sucking, second-rate, dump-it-at-Vinnies crap OR stuff that basically ain't that cheap to begin with (eg. 'free' photo sittings', buy 1 get 2 dinners at some outer-suburban all-you-can eat dive, clothing vacuum storage kits (WTF?), CD storage bins (hello?), 'discount' golf days valid Tue-Thu (..great...)). So, in a saturated market, if you're selling something that's really much much better than the rubbish out there, you might stand a chance. But remember in Australia, while there's a good economy, people are spending less and less money on discretionary items ie. group-ons stock in trade.
(I just re-googled groupon in Australia and had all these views confirmed again. Utter sh**t!)
Ted S nailed it: the website is the easy part. To make it really work the owner value add is in being a) a gun negotiator and b) having a supplier contact list an arm long. The few Australian sites I checked (not that main one) looked like they didn't have either of these two qualities (I mean how hard is it to negotiate a non-existent deal with an Indian restaurant on Tue-Thu nights. Answer: Not very lol).
Good luck with finding that niche!!