[R-390] Judging a R-390A for potential purchase

[Craig]

Questions on how to buy a R-390A.

I'm my area there are never any R-390s for sale. My only options are to buy something from Fair, buy from a individual on the net or buy one via a ebay auction. Most I see on Ebay auctions are being sold by people that know nothing about what they have.

Please see this ebay auction.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5785656186

Description isn't very helpful and pictures are small and hard to tell condition.
Looking up production history on Chuck Rippel's site tells me that there were 5 or more built by Amelco. 
1962 Amelco 35064-PC-63      5 (?) 
Serial number is 2179, so I'm guessing Amelco made more than 5.
I email the guy asking questions. This is his reply:

  --
I just opened it up....It looks very very clean and complete on the inside....only a few signs of surface aging...It was obviously kept indoors...I found it in the garage of an old house that was being demolished....Dont have my digital camera or I would take more pics of the inside....
  -- 

Given what little information there is, how does one come up with a reasonable value for this receiver?

It ultimately sold for $610. A checked receiver with replacement meters sells for $600 from Fair. Which would be a better deal?

Or is it all just a crap shoot regardless from where you get them?

Thanks

  Craig
  westerman at cableone.net