Investment angle?
Darned few guns are good investments. (It happens, but its more luck, than smart buying on the part of the collector.)
When you figure in inflation (and how the value of the dollar declines and buys less with each year), even some of the fine WWII Collectible Lugers aren't a great investment, compared to an aggressive mutual fund.
A SIG or Colt you paid $600 for in 1990 would have to sell for $940, today, to just stay even in what the money would buy.
If you've got some guns you bought many years ago, and remember the purchase prices, use the inflation calculator, here
http://www.westegg.com/inflation/infl.cgi to see what they're really worth. It'll scare you.