Let me chime in on this one:
A working asteroids machine usually sells for 500-1000... (Yes, a large price range, but, these things have lots of flux)
Parted, the working parts sell for:
Vector Mon: 200-300
Boardset 100-150
Empty Cab: 20-50
Harness: 20-50
PS: 10-15
Atari lit buttons: 20-40
Marquee: 10-20
You may make a little money parting it, but it would be worth your time to try and fix it and sell it working. The most valuable part of Asteroids is BY FAR the vector monitor.
If you can solder, a cap kit usually fixes a G05-802. (Does the monitor have 2 boards or 3? a picture would help) This quadroples the value of the machine. Easily.
Next, if the boardset isn't working, the easiest thing to repair are the ever crappy atari fingerboard connectors. Simple as pie, and often fixes many problems.
Having a DMM handy to check fuses and voltage out of the Audio Regulator board helps too.
Really, a non-working asteroids won't net you much.
The marquee lamp is bar-none the easiest fix of them all. A new starter and bulb fixes 99.9% of them.
I restored my asteroids, so if you have any questions, just ask!