Groupon clone, claims to be open source but blatantly is not, pro version starts at $145, premium is "contact us" pricing.
Seemingly simple Groupon clone script for $69 USD, paid in Brazilian Real's. :-)
Good loooking Groupon clone with a seemingly low $200 price tag but a huge list of extra paid-upgrade modules.
One of the many sites that appear to offer identical groupon clone scripts for $400.
Nice(ish) looking groupon clone, $350. Appears to be built on PHP / MySQL. Looks like a unique product, unlike many of the others that appear to be clones of each other.
Open source groupon clone built on django. Some uptake and support. Released in 2009 under MIT license.
A groupon clone site from Agriya, an Indian software company. No pricing information readily available online. Featured in the New York Times apparently, hap tip Glyn. Built on CakePHP.