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

If you don’t want to ship you’ve drastically limited your market. If you don’t have original shipping boxes, you’ve likely devalued your sale by 10% even if you do a good job with packing. Your item is unlikely to be worth more than 50% of the commonly available retail price (which is not the same as list price by the way) unless it’s virtually new or in high demand. That’s my experience. 

I sold 15 items here this year alone. 3 of the items were over 2K and I had no problem selling any of the items. Most sold within 3 days and only one item went in 12 days. I have had no problems selling, but did have a problem with a buyer who accused me of selling a broken Magnum Dynalab tuner. He had terrible reception and jumped to conclusions.

Rare items in high demand is a separate category.

Most stuff I see today is over-priced..I was looking at picking up a Parasound P5 preamp and the lowest price I saw used was $800.00
plus shipping. They were only $1k brand new.

But the funniest things I saw were on ebay, some Russian and Japanese sellers really look for idiots, they might themselves be idiots as well. I mean both equipment and records.