Meh. At first glance, the number is low—about $40k a year if you are massaging on somebody else's table. Just not that great. It's the trade-off you make to work in a room with lit candles and a pitcher of water with fruit floating in it.
However, a large number of massage therapists only do this part time, so as long as you supplement spa massage work with other work (like being a real therapist), you should be able to make a very nice living.
But if you do have clientele who will pack your schedule tight, you can make a bundle. That is, if you own your own place—spend, say, $2,000 a month for rent and the various towels and lotion and whatnot that you need, you have a fixed cost of about $24,000 a year. Now load in clients. If you’re good, you can legally make $100 an hour or more. Work weekends and see maybe 40 clients a week and that’s 4 grand a week or $200k a year in revenues. Net of your rent and that’s $180k a year with all kinds of tax deductions and other niceties built in. And then if you become the spa owner and have a bunch of therapists working for you, you could multiply that number by ten. Nice gig if you can make it happen.