I ended up buying two (and keeping one).
The first one was a no-brainer. It was monitorless with a trashed cabinet, but they pretty much gave it away for $75 (you read that right). That was December, 2011.
$75 is a mega-deal for the PCB alone, but along with that I got the control panel, all the art (in good shape), coin door, mechs, everything. Just a really messed up cabinet. I bought a monitor from someone nearby for $150 and was up and running.
In April 2012, I spotted a local Donkey Kong Junior for $350 in a fully-restored DK cabinet (that was still blue). Also impossible to pass up.
So I bought that, put my DK PCB and art into it, and dumped the janky cabinet.
Now along with my complete DK, I have a Junior PCB, a spare monitor and power supply, and assorted bits and pieces, all for about $600. I made out pretty good.