The expectation of a tip above the price listed by a private masseur is different than that of a masseur working at a spa. Since the private masseur is pocketing the entire payment unlike the spa masseur who is only receiving a % of the fee (usually around 30%). Of course, if the private masseur treats you very well and goes out of his way to relieve your stress and put a smile on your face, you may feel obliged to tip. From my experiences, the private masseur is grateful when you do but doesn't expect it.