Same thing happens to me. I bought a WYSE terminal board that I thought was blacks as well (were any MX versions anything but blacks) on eBay. Contacted the seller since he was only an hour away to see if I could pick up and pay in person. I get down there and turns out the seller works an an e-recycler. I was looking at the board and turns out it was the rubber dome version. Needless to say, me and the guy got to talking about keyboards and he had 2 more WYSE boards in MX. He let me buy those two for $3 each.
Now every time I go down there I try and stop in. Last time I was there I got a PS/2 plug Model M and an AEK II for $20 total.