Ok, so I just talked to representative from AV For Sale. Their website is here:
www.avforsale.comThey are a warehouse for surplus Audio/Visual equipment out of Atlanta, and they used to sell a lot of nice monitors.
When I talked to the rep he said that they mostly can't sell them anymore and they just end up recycled!
He said they would ask $25 each for a Sony PVM 2530, and would have to look into the NEC XM29's and Mitsubishi equivalents. I don't expect them to want much more for those. The shipping would be about $100 on each.
The AVforsale guys know what they're talking about with this stuff, and they used to post detailed descriptions, and even a photograph of a test pattern of the monitor you were purchasing on ebay. I would trust them if they say that a monitor is in good condition.
This is a PVM 2530:
They're 15khz only, and to use them properly you have to construct a VGA to CMPTR port adapter. It's not a big deal, and several users from this forum and the schmups! forum have done it, but it is something to be aware of before jumping into a purchase.
Don't believe the washed image above. The image on a working, calibrated PVM is crazy good. There is not a single arcade monitor ever made that would have as vivid colors as one of these would have new.