I agree on Ebay, which is where I got my copy for cheap. It seems to be one of the more available DGP titles. Dragontrove is good albeit sometimes charging higher than what you can get on a game if you wait but 1) he does have the game 2) it is usually in very good condition (he seems geared towards collectors)
I've dealt extensively with Sentry Box over the past decades. Good store. And they are (if you ever get to Calgary) absolutely fraggin' huge. More square footage than ten or twenty of your average nook-in-the-wall FLGS.
(This is an unsolicited and unremunerated testimonial, but should not be construed as advice for any purpose, use or in any legal sense. Use at own risk. All lawyers should be fed slowly to crocodiles... *grin*)
The Sentry Box in Calgary is one of the best gaming stores on the planet. Gord (owner) & Sean (active Traveller enthuasic) helps keep their stock current and always approachable.