I did a 34 quid deal , sold about 120 , got £23 from Groupon off each deal, job average was £60 , plus lots of referrals, plus ongoing work I am still doing 18 months later, well worth it if you are sat twiddling.
The suite and carpet deal is bonkers though , you need to negotiate HARD with Groupon , over several weeks , get them down on their commission % and up on the deal price , then down on what you will do , all the time juggling your normal price detailed on your website , it is very complex but if you know your numbers you will turn a wage, not a decent profit though.