If you aren't familiar with doing your own auto repair, you may talk to other people in the parts store, the local garages, at car shows, cruise nights, swap meets, etc.Is there any risk involved?
The car could've also been in a flood which will cause the electrical system to go out sooner or later.
Because these cars are sometimes used for unsanctioned racing you can usually find imports at the junkyard.
"Pick a part" type auto parts businesses tend to work with salvage and insurance companies to get choice wrecks, and while you probably wouldn't go there to get an RX-7 door panel, they are perfect spots to find interior RX-7 parts and engine parts.
used auto parts that come from "pick a part" yards are usually pretty cheap because you are doing the finding and removing of the part all by yourself.
Pull the trigger and it's not making contact with someone or something and the gun produces a bright and visible arc between the electrodes and makes a loud snapping noise.