I have bought and sold many gun and reloading items on Ebay. There is no mystery about it at all. Whether you are a buyer or seller the first step is the same, i.e.;
1. For several days, look at your item of interest for sale by others and place them on your watch list and forget about them. Come back in a week or ten days and see what they sold for. That will give you an idea of the general price point for the item. Then you decided if you want to sell or buy for that general price.
2. If you want to sell, place the item up for bid with a low starting price, no reserve bid and reality based shipping costs. Then forget about it. Most of the times you will get about what you expect, sometimes more and sometimes less. Just take your profit or loss and move on. That is just the way of life.
3. If you want to buy, figure out what you are willing to pay, then use some online bidding program. This program will make your bid 7 to 15 second before the auction is over and you either win or did not win. By using one of these programs, you don't trigger or respond to auction fever. In ether way pay what you owe, continue looking and bidding or just go play golf or watch a movie on TV. Whatever you do, don't watch the bid on the item and try and top the bid of another, that is how the foolish auction fever starts and the origin of idiotic prices on some items.
Ebay is our national garage sale where items can be found with ease that would take you years of searching locally. It is a good place for wise buyers and sellers to trade, but a bad place for idiots to try and do either.
Addendum: Ebay is NOT the place to buy a new anything. Whatever it is you are looking for, 99.99% of the time you can buy it for less from some online merchant. Ebay is THE place to buy used or out of production items.