I have been fortunate enough to win 2 Ebay auctions a couple days ago. One auction was for the 1st Edition Gamma World rulebook, which I scored for around $10.50. The other was the 1st Edition Gamma World Referee's Screen with the Erol Otus artwork, and 4 Modules: The Legion of Gold, Famine in Far-go, Cleansing War of Garick Blackhand and Mind Masters. That was for $38.00, so I think that was a good deal. They are currently on their way to me and all I can do is wait. I once owned the referee's screen and both the Legion of Gold and Famine in Far-go modules a long time ago, but I got rid of them in some fit of madness.
I am unfamiliar with the other two modules, so hopefully I'll be able to use them in the Xhuul game. No doubt there will be necessary changes to be made to fit those modules into the Xhuul setting. For instance, Famine in Far-go's mutated chickens have no place in Xhuul, I'll have to come up with suitable replacements.