Most quality bathrooms appliances in Thailand are brought in from abroad and if you do that you need to add tax. But if you moving here and making a house you can actually bring one container with stuff totally tax free. Well you can not bring 10 TV sets or 20 computers or something like that but one or two of each if perfectly fine.
If you consider moving to Thailand and building a house you check out taps4less.com online bathroom shop. They have a good selection of taps, showers, baths, bath tubs, shower enclosures, shower valve, bathroom furniture etc
Buy what you need for your house in Thailand online and then ship it over with the rest of your stuff. It will be cheaper then buying in Thailand and its tax free.