If you want to stay close to the circuit, you will be in or around the town of Buriram itself and while there is a decent amount of accommodation available be sure to book well in advance of the race weekend as hotels do get fully booked with the organisers, teams, and fans rolling into town. Booking online and in advance will usually get you a much lower price.
Guesthouses are the cheapest option and expect to pay 500 baht (USD 15) per night for a private room with internet access, plus daily room service – however, you may find that some only include shared bathroom facilities.
Local style Thai hotels are priced around 200 baht-800 baht ($6 - USD 23) per night with the higher end of this scale meaning you get air conditioning and a TV in your room, plus the benefit of a private bathroom.
Hotels catering more towards tourists cost around 1000 baht (USD 29) per night and may offer a swimming pool for guests. Business-centric or hotels at the luxury end will cost from 4000 baht ($116) per night and are indistinguishable from top quality hotels elsewhere in the world.