Hi proofpositive,
you will have several things to consider:
1. Numbers - Groupon are notoriously bad at agreeing and then sticking to maximum sale numbers - it is not in their interest to limit the number of sales, as they get 100% of the sale price if the buyer never redeems their voucher, and of course, whatever their agreed percentage is on the ones that do get redeemed. For your promotion to work you MUST ensure you have a strict limit on the number of vouchers sold, otherwise you will be working from dawn till dusk for a long time, for very little money indeed.
2. Price - As a rule, if you sell the single session normally for £130, they would expect you to offer it for at least a 60-70% discount (note AT LEAST), so you'd be looking at selling the voucher for around £40. Of this, you would get between 40 and 50%, so your take home for each of these vouchers would be in the region of £20.
As you can see, this is a massive hit for you. To be perfectly honest, I never know why businesses do a groupon promotion for any other reason than as a loss leader.
In our business it worked well, but then we have an 'introductory offer' - 15 days access for £29.99. Everyone is entitled to this and it gets people into the business, and we then work to retain them. We do class based offerings, so individuals do not hit the bottom line directly. One of our offerings after that is 10 sessions for £125. So, for our groupon, we offered the ten sessions (essentially instead of the introductory offer) for £28. This looks like a huge discount - £28 instead of £125, but actually is instead of the £29.99 introductory offer. We still only took home just over £14 per person, so we were losing 50% of our intro offer take, but we got a lot of people through the door, had a pretty good retention rate on those and it proved more than worthwhile.
How likely are people who take your stop smoking session (and from whom you get £20) ever to come back to you? Do you rely on repeat custom from the same people or are you more likely to need a steady stream of new clients? If it is the former, consider it, if the latter then I strongly suggest you don't use groupon, as all it will achieve is minimising your take!
In a nutshell, groupon is *almost* a 'try before you buy' advert. If people don't need to buy after trying (i.e. it's a one-shot product/service) then there is little point to it for you.