225 for one of these is about average price I'd say. I have seen being given away, and I have seen them sell for $1000.
The monitors in these are swappable with no modifications right?
Sounds like you will be able to get at least one 100% working. By mixing parts from one to the other you should be able to come out with a very nice cab.
Like others have said, "I think it's a fuse" is the oldest one in the book.
What's a "tune up"? I've never heard that term in relation to an arcade machine.

Rotate the microswitches? Change the spark plugs in the CRT?