You can look for gyms in Bangkok first because they're likely to be training some star players in the milieu who frequently have fights in Raj or Lumpinee and they vary in cost and services. If you look for those high profiles with top fighters, it can get quite pricey in or out of the city. For example, Por. Pramuk gym could charge a lot more than what they'd ask you to pay in average gyms in Bangkok. So unless you particularly prefer the country side, you can shortlist the candidates in the city and then look around, talk to the trainers before you decide to check in. I personally liked training in Muay Thai Plaza. It's a few minutes away from Lumpinee stadium and you'll have mandatory jogs in Lumpinee park every morning and afternoon before practice. They have fighters coming in and out of the country so you can learn from them and spar with them, too. I also hear that Sasiprapa is authentic and friendly.

yeah, they are bunches of them, indeed. i really not in this bussiness. so, i'm afraid would make any misrecommand to you. so, be patient and post more in others furums to get the real sharing from whom had experienced it. i have friend, he went for short term (a month) training too. itz somewhere in khonkaen (maybe ?? could no remember it) too bad i can't contact with. good luck.

do you want to learn boxing?