Tell him to pull out each upper sparkplug, pull the EFI fuse (dr. side engine bay) and test compression on each rotor. That will be your first step in checking the engine. I have bought several RX-7s in which it was assumed by mechanics that the engine was bad to find out a few bucks later I had a great running car.
Also Drftk1d, I believe she was stating that the car was $200, and not the ECU quote.