I had a nice room with full breakfast for less than 125 a night at the Marriott. Yes, I know expensive for Thailand but I love the hotel.
Lookin, you can get rooms in the gay area for around 50 USD a night. see:
http://www.ambiancehotel.com/
http://www.caferoyale-pattaya.com/
http://www.copapattaya.com/
If you wish your own apartment, firecat stays at condos for around 50 USD a night I think. He loves it as total privacy and your own room near the big mall. He uses a service to book. Let me know if interested and I'll get info.
Also, there are tons of cheap hotels for 25 USD a night. But, the ones listed above I know and would have no problem staying in any of them.