Massage
As with any trip to Southeast Asia, massages in Bali are cheap. Massage shops are everywhere, too, so you can pick a decent one and simply walk in. Prices vary by shop and by type of massage, but a basic full-body Balinese massage for one hour seems to run about 120k rupiah.
My body tends to hold a lot of tension, so I got a massage about twice a day in Bali. There are all kinds of massages, so I tried some unusual ones. For example, I tried foot reflexology. I think reflexology is pseudoscience, and I don't really believe in it. But whatever the rationale, my view is that if it works, there's no reason not to try it. It isn't a full-body massage either, so it's much cheaper.
Having tried reflexology, I can't say I felt any special boost to my health. Honestly, like at any massage shop along the street, it's hard to expect real expertise in reflexology. I wonder whether it differs from an ordinary foot massage in anything other than the added acupressure. Still, I got around on foot, so my feet and calves were badly knotted, and it loosened them up well, which I was happy with. As the saying goes, any road will do as long as it gets you to Seoul. Whatever the rationale, all that matters is a good ROI.