Without full information, 1 rule of thumb is monthly expenses tend to run about 4X rent. If that were true, the annual expenses for this salon would be $81,600.
If you figuring paying someone (even yourself!!) a minimum of $7/hr for 12 hrs/day for 7 days/week, that would make payroll of $2520/mo. Plus adding advertising, other utilities (phone), supplies (lotions,
bulbs), etc etc etc. I'd say 80K/yr is likely. And that assumes all the beds are paid off of course - you wouldn't be taking on any leases.
SO - how much do YOU want to offer for a salon that MAYBE broke even in year one (which is tough to do in the best of circumstances) and then got LESS successful the following year??
Without seeing the rest of the numbers, I'd say they should hand the keys over to you to allow them to avoid getting 'stuck' with the rest of their building lease commitment and you see if you can make a go of it. Otherwise, I can't see being interested.