My family will be moving from Chiang Mai back to the Chonburi/Pattaya area next year. I'm looking for a  good quality, yet affordable high school for my 14-year-old son. Currently he attends bilingual Christian School in Chiang Mai. Any recommendations would be greatly appreciated as there are a scarcity of listings on the internet.

If the Christian angle is of particular interest, then consider Assumption in Sriricha:

 

https://www.acs.ac.th/

 

Otherwise, Maryvit or Satit.

 

https://pattaya.maryvit.ac.th/

 

https://www.sus.ac.th/

Check out Royal English Program in Ban Chang. Tuition runs about 140K/yr

I sent my son to Burapa International School in Pattaya which was good and not too expensive, but they didn’t teach him how to read or write Thai. I transferred him to Aksorn in central Pattaya. They are not expensive, most classes are in Thai.  They had an English program and swimming classes as well. It’s a step up from the public schools but it all depends on what you are looking for. Good luck on your search.