Accommodation

I’m heading over to Thailand for training and looking for accommodation in either Pattaya, Bangkok or chiang mai. Does anyone know any sites or places I can go to look about renting monthly for a minimum of 3 months for around 5000 baht or less? Im solo male and happy with a very basic place but preferably close to the city centres of a few km out. I’ve done the hostels before and monthly they work out about 4000 baht so it’s decent but I’d prefer a place of my own this time round. Willing to stay at Muay Thai gyms also as long as around 5000 baht or less a month