You can donate your body to Chulalongkarn University, where it will be used for research and/or instruction for medical students. There are some exclusions though: body too decayed, rabies, HIV, Hep B and C, active TB, advanced state of cancer, radioactive implants within last six months, death due to accident where possible legal issues are involved. You'll have to prearrange or have your executor coordinate for travel of your body to the University. They'll have 20 days to do what they will, after which they'll cremate whatever is left and provide ashes to whomever you stipulate. Only cost is the freight to get you there. This is about as no frills as it gets in Thailand. You'll have to go to Chula University to register, but only takes a few minutes to do so. Make sure to bring your passport. For more info call them at 02-256-4751 or 02-256-4281.