Depends what area of Thailand and what areas you wish massaged. I had a great 2 hour massage at lee gardens in hat yai last weekend for 400b, nothing better than watching a great football game while getting massaged, although the game isn't really conducive to the whole relaxation bit lol. Foot massages can be had for 50b just about everywhere, but I'm not sadistic enough to try it again, not a big fan of pain. Some places are a bit more pricey, and extra services can tack on to the price as well. If you go to the resorts massages can cost you a bloody arm and a leg. Anywhere with high tourist traffic, or rather high money traffic has pretty high prices, but still relatively inexpensive compared to what you'd pay elsewhere in the world.