A combination of both. Some of the rarer pre-ban stuff (Steyr AUG, etc)...and some of the truly rare stuff, some of which I own, some of which my Father owns (M1-Ds, 1903A4s, a couple WIN-13's, some original M1 Carbines including a paratrooper, M97 Shotguns, etc)...
I tend to collect the more modern/"rare" things, he tends to go for the older stuff. I'm starting to get his older martial arms bug, though.
Generally thought: If we can't pick it up and take it to the range (Including the muskets)...why bother? I had/have a NIB Norinco underfolding AK, got it a couple years ago. First thing I did when I got it, was clean it. Wiped all the grease off.
Second thing I did, was shoot it.
If you're going to get it, why not use it?
The truly rare stuff (A US stamped Johnson rifle? Haven't seen one yet) I might not be tempted to shoot. Haven't seen a Pederson Device, either (Tho we have a couple 1903 Mark I's we're dying to try)...
As far as "modern" rare things go (Walther WA2000, SIG 550/551's)...Nah. I'd love to have one, but not at those prices, not if I can't shoot it and enjoy it. Not that I'd mind one if one was handed to me for free.