yeah, we all see this for recent models. Some times a new hot model will start out high since demand is high and supply low. Case in point would be Kel-Tec's PMR30 which for a while could not be had for anything under $499. Now, supply has caught up with demand and the prices have come down. Yet, yahoo's who bought when they were high don't understand they can't sell them now for what they paid a year ago.
Same has occurred recently with the AR15 platform. I have a franken-AR that has a PWA lower and a Colt M4 spec upper. I paid much dinero for it during the Clinton ban. Now, with every gun maker flooding the market with pretty good ARs, I would hard pressed to get my $$ back if I sold mine. Win some / lose some!
Now, when you start talking about collectibles, then all bets are off. For instance, there are many S&W revolvers for which older pre-lock prices will be higher than current production. Why? Because people (like me) simply like/value the older (aka, non MIM, no lock) guns better. I will not buy new production. And anything that has a cult following and is no longer in production may command astronomical prices. Case in point - Colt Pythons.
Then you also get folks who think their custom this or that is worth a fortune. That's like thinking that you'll get your money out of all the upgrades you do in a house. You may, but you may not.
Big LSWC's rule