I've signed a finder's fee agreement before. All I would have had to do is send an email intro to someone who eventually invested. I believe it was for 10 or 15% of what would have been raised.

If the "finder" is an investment banker, this seems very low.

As a rule of thumb, investment banks will charge about 7% of the value of a stock issue for an IPO.

So, for comparison a ~$1B IPO (which this round was comparable too) would have earned a bank about $70M in fees. By that metric, only paying $7M in fees seems cheap. Even assuming the lawyers/diligence/audits/etc cost another $10M (and I suspect that's probably way too high), Groupon is still getting off pretty cheap.