The first time I traveled to Saudi Arabia, I went with experienced GIs to the markets to learn how to haggle. Unless you do a lot of used car or other secondhand sales, you just don't have the experience or know-how to barter.
Now that I've been to Saudi several times and South Korea more times than I can count, haggling over price is not a big deal. No sense in getting emotional.
It's pretty simple. The seller asks their price for something you're interested in buying. You offer what you think that thing is worth to you, or what you think is a fair price compared to other sellers. You have to be willing to walk away in order to get the seller to lower their asking price. In the same way, the seller has to be unwilling to accept a too-low offer if he thinks someone else is willing to pay more.
Supply and demand drives prices. Shop around. Do your homework, and use the information you research to back up your position when haggling.
I imagine most of the emotional responses stem from being frustrated over the process because you don't know what price the market will support.
A firearm's "value" to you might be super low to another person, AND it may be super high to someone else. There are those looking to "flip" anything they can: firearms, cars, houses, etc. They look for desperate sellers in need of cash and try to pick up a bargain -- only to turn around and advertise it for higher. Or they may already have someone they know will pay more for it than they did.
If the only offers you get are low-ball, maybe your particular firearm isn't in high demand right now? I've seen some ads sit here for months and months before selling, because the seller hasn't found that one buyer who will pay what it's worth. It's just a matter of timing.
Lots of people bought firearms at whatever the seller asked when Obama was in office. Now those guns are commanding a much lower price due to over-supply and less demand. What you paid is not the gun's "value". It's value is based on what a buyer is willing and able to pay for it in the condition being offered.
To me, this is all basic knowledge regarding markets and pricing. It doesn't benefit anyone to throw a fit and accuse "the people" of expecting to "get something for basically free." That's not only a blatant exaggeration (I seriously doubt anyone was looking to pay nothing at all, even "basically nothing at all"), it's also blasting everyone on here who never answered one of your ads.
If you can't handle the "pressure" of haggling with someone who's simply looking for a deeper discount than you want to offer, that's YOUR problem. It's so easy to say, "No." Taking a lowball offer personally? That's something you just have to learn to get over. Maybe you REALLY REALLY need to sell a gun for whatever reason. Your situation becomes a lowball buyer's advantage. Nothing personal. It's just business.