Do people really just not get it that their items are not selling...

There's a truly profound & deep as the ocean issue at play here.  The incontrovertible source of the reflexivity embodied in the often stated sentiment, "I'm not giving it away" needs to be understood. The resistance of many sellers to doing so is ferocious.  It has to do with control issues fueled by unexamined & undealt with emotions that they are often too unwilling to remotely deal with - choosing rationalized denial instead.  The economics here make this more then clear much of the time. Money represents 3 things only - time, effort & energy.  The first in particular is an irretrievably, irreplaceable commodity.  One that so many are prepared "to give away" (in addition to the other two) to pursue what is often the illusion of gaining the prosperity money is a component of.  There are partial exceptions of course - such a when you need to finance something specific with X amount of dollars that cannot be easily supplemented by other resources. This is too rarely the case however. All studies show the human mind is wired to be substantially more sensitive to loss then gain.  Actions are precipitated by loss 3 to 4 times as easily as gain. Its a stubbornness built into us that is no longer as rational as when it meant living or dying regarding our food supply when we hunted to eat.  Loss of food stored was always more keenly felt then the urge to go out & hunt (unless we were ravenous).  Our most powerful intellectual attribute, our imagination just intensifies it near infinitely in modern times - fueled by old, deep emotional programming caused by bad experiences .  It makes us weaker as we desperately pretend it does the reverse. All of us - its simply a matter of degree.

Whats required is true strength - not arrived at easily. Otherwise referred to as maturity.  The maturity to realize that when your unconscious tells you that it is time for something you own (or in general) to go out of your life - you let it.  In the most efficient way possible - including  not squandering irreplaceable time (& the other 2) - so you can get on with the next phase of your life. The meaning of life is always most fundamentally: To Learn.  It can really be a B at times & for many, especially here. 

Squandering time, effort & energy can thus easily become negatively addictive while rationalizing it with a vengeance. Notice how many will just double down petulantly when this pointed out to them.  Their masculinity (usually a man) feels threatened & is instinctively responded to. No man is unaffected but the genuinely strong & mature ones have learned to let go.

Whether or not the OP can afford certain advertised pieces of equipment has less relevance than whether he feels the advertised price is justified. Anybody can put any price on anything, and buyers can react in any way they want.  Who cares?

In my case, I usually give away my old equipment to budding audiophiles, especially those that I know have limited means.  For example, I had some 30 years old speakers that I installed "new from the factory" drivers in.  They looked and sounded brand new.  The manufacturer had just issued an anniversary edition for $1500.00.  So I figured I could get - maybe - $750.00 for them.  I had the original boxes, but they were shot, so deduct $75.00.  We're at $675.00 now.  Shipping would be around $75.00 (two boxes), so we're at $600.00.  I would have to find and modify two boxes, so let's say two hours of my time (I make $45.00/hr) and $10.00 supplies, so we deduct another $100.00.  Deduct another 10% for the 1/10 deals that go wrong, and I am at around $450.00 (about what I paid for the new drivers).  At that price, knowing that I would have trouble convincing any new buyer that I had actually installed new original factory drivers, I decided I would get more satisfaction giving them away to a thirty year friend who loves music but wasn't in a position to spend any money on audio equipment.  He was thrilled, and I get the satisfaction of helping out a dear friend and knowing that those excellent, lovingly cared for speakers found a good home!

I have never had any trouble buying things on sites like Audiogon, but selling is a different matter. I am 100% honest and fair, but I have been swindled on a number of occasions.

When I take the risk of selling into account, plus the actual cost of packing, driving to UPS, and shipping, the value of online selling depreciates. I live in a small city (100,000 +/-), so having people pick up the equipment or Craig’s list doesn’t cut it for audiophile equipment (different if you live in a large metro center). I find it easier to sell equipment on consignment. I get less money that way, but all I have to do is bring in the equipment. When I consider the value of my time, it is a better deal!

I've sold about a dozen classic tube gear items on Audiogon at my asking prices.  Classic tube gear keeps escalating in price like my sales of a McIntosh MX110, Fisher 200, MacIntosh MC30s, Fisher 400/500 receivers, etc.  They are now in greater demand than when I sold them over 15 years ago.  I've purchased items for about 50% of retail price as well.  I've had really fine experiences with Audiogon but couldn't buy speakers or cartridges for the same reasons stated previously (won't ship and condition issues, respectively). 

I did just purchase speaker cables at a fire sale price because they are from a highly respected but unknown manufacturer and he was selling long runs (20' and 25') of 2 pairs and a single run of 25' and I only needed a 25' pair.  Tough to sell unknown brands.

I think we all need a "price adjuster" who can inform us ( tell us ) what to sell our gear for. Much easier then to let the market decide.