What are the chances of me finding a gym in the Rayong/ Ban Chan area?

Also squash or badminton courts/ clubs?

When I lived there a couple of years ago the only one I knew of (in Ban Chang) was on the Eastern Star housing compound, but don't know if it was open to the public. Some of the companies on the Map Tha Phut industrial estate have excellent facilities, but obviously you'd have to be staff to use them. You might have to go to Pattaya to find a decent gym/fitness center open to the public.

Kanary bay on the beach has tenniscourts and a fitness centre. I know you can use the tenniscourt if you're not a guest but i don't know the prices.