Ah, another Western-centric term. Thailand is in the Northern hemisphere and isn't at risk of moving South, but whatever, let's have another word for snowwhite western millennials to facilitate their guilt trip.;)
Well you need about 30,000 Baht a month, for a nice place and breakfast. Girls will just give you lunch, dinner and drinks so that saves quite a bit on cost.
I'd recommend nothing at all, and make sure you don't bring stuff that's 110V only, such as some really crap hair dryer. (Must things that you travel with will be dual voltage)