work it out, my condo was $350 a month, had a rooftop pool, it was in Pattaya and called 'The Base', it was in low season tho so add maybe an extra 100 bucks for high season, water and electric was another 30-40 bucks.
food is what you make of it, you can eat like a thai or a westerner, drinking and partying will get expensive....
it's all about how you live.
you need 500 bucks to actually survive tho and have a comfy condo and for bills and cheap food.
but what about visa? you'll need to get a 6 month tourist visa in your home country then you;ll need to do border runs every 3 months plus 1800 baht to extend your visa for 1 month at immigration so you can get 9 months out of it.
then you'll need to do border runs every 3 months which will add up in costs.
if you're over a certain age you can get retirement visa but you need like 800,000 baht in your thai bank to get it.