At £79 (was that for one area?) he would not have been making a profit, as Botox is genuinely expensive to buy - though Groupon is a bit about people who don't show up (you still get paid) or use their voucher, etc, so he should have either broken even or made a small profit.
They say Botox is still quite expensive to buy and never a major profit spinner, as there's only so much you can charge, and that most practitioners make about £50 a person in terms of actual profit or thereabouts depending on their overheads etc. But when you consider that you are in and out of there in about 15 minutes it makes it worth it, and I think that's why you often find Dentists doing it too - they are all set up in a clinic, all trained up for needles and anaesthetics and facial aesthetics etc etc and it spins a bit of extra cash into their practice.
And a botox client will often go on to have other things like fillers, or derma roller (that's got to be a nice earner - buy the roller, train in how to use it, watch the cash roll in as it apparently really works but once you've bought the equipment you get to use it over and over as opposed to having to buy botox), IPL, etc.
IPL machines cost a fortune but once paid off, are a nice little earner too I would think.
Any professionals out there who think I'm wrong about any of that do correct me - its sort of just what I've read in magazines and the like, but it might not be 100% so would love to hear from you with inside info 