It's probably in the electronics cluster behind the dash. I can't think of a reason off the top of my head why an aftermarket amp wouldn't work with the stock speakers, but unless you're planning on upgrading those too there's no real reason to get an aftermarket amp. At best it would allow you to pound music out slightly louder with less distortion. It's probably gonna have to be repaired at the dealer though, and that blows.
I come from a family of mechanics, we have a shop with plenty of tools and a couple car lifts, plus RX-8's are relatively reliable so maintenance is not a worry.
Rotary engines are reliable and that's nice, but do realize you're buying a car with 150k miles on it. Sooner or later something is going to break, and given the age and wear on the car I'd say be prepared for sooner rather than later. Since you guys are mechanics then that's great, you should be able to fix it up at a low cost in no time. I'd just give you the same advice I'd give anyone else looking at a used car, make sure it's in good condition and has no current problems you have to deal with. Ask the seller if you can take the car to a mechanic (youself if you'd like) to check it out before making the decision.
Poll