The point I am making is that so many things are described as UNC and people will bid on them because they are so described. If you don't put unc in the title virtually nobody will look at it, but the truth is that UNC coins make up a tiny fraction of one percent of the total population. Some are aware of this but many aren't. This thread exists in large part because of delusional sellers and buyers alike. It is like 'rare' on ebay. About 8 or 10 years ago in this thread I took the first 25 'rare' coins and separated out the rarities. There was a 1934 halfcrown, which is scarce in high grade, and an 1853/2 halfpenny which is at least verging on rare. The rest were 1967 penny type material. Descriptions are best ignored.
The volume of listings is such that I believe it has conditioned people to expect most things to cost 99p or not much above because there are too few eyeballs for widespread competitive bidding. I usually list some piece of junk that has a chance of selling even at a quid, just to get a card out and advertise the site and so open eyes to the fact that there is a world outside ebay. I would also like to add that it is not a very successful method, but hope springs eternal. Ebay is just another place to buy, not the only place.
Most dealers do not make 50% + VAT. 20% is closer to the mark for a typical sale, (and the VAT is applied to the margin, not the full price), though clearly some things slip under the radar and are acquired cheaply. Whether you buy on ebay or from a dealer, you will have researched the coin just in establishing what you want. Investing is buying cheap and selling dear, just as it is for everything else.