In the same boat as you ^. After the the X1800XTs 256 disappeared I am seriously looking at the X1900GT, you get the same or better performance in some cases, more OC headroom, 36 pixel shader units...I think you can pick one up for about the same price as those X1800s.
I would try looking on eBay for the 256 X1800XTs if you really insist.
1900pro is supposed to come out on October for $200... Faster and probably runs cooler than 1900gt since it's build on 80nm... Who knows this can probably hit 1900xt speeds with the right voltage and cooler..