I sold my HK because I paid $240 new and got $1000. Please don't ignore the market prices have a large influence on retaining a marginal (to that owner) firearm. Not everyone can afford the care and feeding of an arsenal of firearms, so the ones that typically fall into disuse will be sold for a variety of reasons, especially when the perceived value skyrockets.
There are other reasons to sell. Some guns just aren't flexible in what you want - HK's have grossly expensive accessories, the HK scope mounts went to $450 at one time, mags were horribly expensive until two years ago, and the only options on furniture were expensive - slim handguard, fat handguard, and color. Wood if you stumbled across a set. Choate alone had more options for the Rem 870 pump shotgun. The FNFAL, AUG, etc are all the same - no aftermarket support anything like the AR.
Then there is application - an HK isn't the lightest option for a woods gun hunting deer, is hard kicking compared to the AR, and doesn't get the job done any better for all the work. Same for Rem 700 bolt guns with scopes - don't crawl the stock, keep the power down for fast shots, make one shot count because deer can run faster than a bolt can be cranked in heavy cover. They don't have to go far to be lost.
So guns that don't help hit the sales table for those that do, and that's just the users view. Lot's of casual traders buy into a gun at 10% less than the going rate and wait to sell it at 10% over because their glib tongue and manners can get it. They just like to hustle the sale. How many of us can count the good deals at a gun show on one hand, but on the other, well, there's 400 tables of stuff that go right back out the door on Sunday evening - for the show next week 200 miles away. These guys don't negotiate much because the ups and downs of the business tell them they can wait it out, it will eventually move at their asking price.
Even in this economy, guns don't get sold for a loss very often.
