I used to think it was an industry with low barriers to entry, as did lots of people who have lost lots of money on Groupon clones. I'm not sure why, but it turns out to be a really tough business for all but a few companies.
You need to be very good at signing up businesses and getting good terms for your company to succeed. In addition, you need to figure out how to get a stable base of customers of your site.
Basically, Groupon clones have very low technical barriers to entry, but if you don't have a really good sales and marketing staff you're in trouble.