Well I used to work in an arcade on a beach boardwalk fixing machines....
The owner also owned a TON of rental cottages, the really trashy places had all the interior walls gutted and were used for storage of "retired" arcade machines...
One day he told me to get the truck and throw out everything in one of the cottages (about 50 machines). Most of them were really junk, things like old redemptions machine, or good games that had been totally striped for part or broken... I asked if I could keep a few machines my boss was like "I don't give a shit what you do with them just get rid of them"
I salvaged a Double Dragon and a Ring Kings machine for myself and got an old Contra machine for a friend of mine... the rest went to the dump (I would have kept more myself but I had no place to keep them, as I was staying with my parents for the summer before going back to school. I also grabbed an extra working monitor out of one of the other machines.
I later ordered 2 broken UMK3 boards from ebay at about $20 a piece... one had corrupt EPROMs and the other one had busted sound... I ripped the good EPROMs from one one with bad sound and re-programmed the busted ones. Then I found a junk machine at work to repair the sound on the other board. After that I converted the Double Dragon machine... The instruction booklets that come with the machines often have the controller panel patters in them. I found an MK2 machine in storage at work and photocopied the patterns out of it and made a completely new controller panel from scratch. I sold the 2nd board I fixed for about $75 and used that to buy new buttons and joysticks for the panel I made.
As for the Ring Kings machine I broke the monitor trying to rotate it (it was vertical and most "worth while" games have horizontal monitors). So I though "no worries that's why I grabbed the spare" to my dismay my mother tried moving it and smashed the back of the tube... I'll probably just junk both monitor and grab a nice big PC CRT for a mame cab or something.
You can find a decent cab for about $500 +Shipping on ebay and game boards for that era rarely go over $100... if you look hard enough you can probably find a whole MK3 machine for $500...
