As we run www.discountvouchers.co.uk
I can tell you the numbers
Sales numbers are huge
Commisions are rubbish
Competition is huge
Simple problem is unless you have decent money to throw at it you will get swamped and waste your time.
Traffic 100-200K per day mostly from organic
Revenue about £1 million per month
Profit £4 million in 2009 accounts
Traffic 100K per day -20K from organic, rest from ppc and/or email
Revenue about £300K pcm
Profit......no idea but minimal depending on growth plans
Spend so far about £3 million
Traffic 30-100K per day from organic, ppc and email
Revenues £100-300K pcm
Profit - none, actually so far huge losses
Spend so far about £2 million and plans to increase this massively
There really are no other players in the space that are growing. The next 3 players are all loosing market share and are not geared to grow.
The target of the top 3 is Groupon
My advice is find a niche where you make more per visitor.