Yeah, they are somewhat collectible. Most of the original supplement books are pretty cheap to pick up ($5 or less). Merchant Prince and Robots the notable exceptions. Most of the
GDW adventures are pretty cheap as well. The last two, Secret of the Ancients and Signal GK, are much harder to find and usually go for more.
And sometimes you get lucky:
** eBay auction listing blocked. Please enable cookies in your browser for this site and for eBay! **Azhanti High Lightning used to go upwards of $100 a few years ago. Now you would be lucky to get $50 for it. And it used to matter if it was complete with the Lightning Class Cruisers supplement but if you look at some of the recent auctions on Ebay, that doesnt seem to be the case anymore. But if its in nice condition and unpunched, odds are you will still get a pretty decent price for it.
You don't like your job, you don't strike. You go in every day and do it really half-assed. That's the American way. - Homer Simpson