groupon concept is used by many people now a days
when the groupon was a success,another company started groupalia in spain with the same concept and earned millions of dollars in the same year.
but now its getting saturated as many groupon site are being made by people who thinks it will be a success.When groupon was there,there one and only one groupon and now if you want to compete with the leaders,you should first think about the marketing plan before you purchase any script.if you cannot market the website,the all the money which you had put on making websutea and the domain and hosting will be in loss
Do not create the website yourself as its a complicated and sophisticated website.there are scripts which are available for low price in the market but some wont have the necessary on site marketing features in it.so make sure before you buys it.
you can then customize the design to get a new look.
The best thing is to buy a groupon clone. The start from 0$ to some thousands. It only depends on the features you want available.
You should search for yourself for suggested groupon clone as everybody will suggest the best he likes ( not the best for you ).
I would go with the one from Agriya.
another view on the subject is that you visit www.snempire.com They sell a script on which you can build a social network and there you can insert your sales links. Different approach but maybe easier to manage. Up to you to decide.
I wish you the best of luck!