Just a little plug for this place if you ever find yourself passing through Rayong. I paid 800 baht a night on Agoda and you can't fault it for the money.
Golden City Rayong Hotel – โรงเเรมโกลเด้นซิตี้ระยอง
Rooms are basic but clean with plates and a microwave; there's also a night market opposite as well as a 7. A small pool and gym are also available and you get a buffet breakfast thrown in (Ayam beans and crappy ham if that's your wont).
Although it's aimed at business travellers, there were a few tourists there too who were doing the same as us or had decided to check out the beaches nearby for a couple of nights.
I would use definitely use it again.