BUYERS, What Issues have you had with Sellers and Listings that Prevent you from Buying?

A fair amount of sellers also won't provide a shipping cost until you commit to buy as they want to make sure that they pass on actual cost to consumer. However, this creates friction as the buyer wants to know what they are paying before they commit. 

2) Use Hi-Fi Shark or sold listings on ebay to determine market price and then go down from 5% to 10%,

What is the logic of going down 5-10% from sold listings? 

I think it's simply basic economics, supply and demand where the demand isn't there at the moment and the main thing that drives demand in most markets is either a shortage of supply or a reduction in prices. In other words there isn't enough of a product people actually want , supply, or there is to much so you have to reduce the price to increase demand. 

There are so many things besides price that turn off potential buyers or cause them to bid lower as a hedge. A very good seller with a very smart listing will get more money from the same listing than a seller who is putting out signals that erode trust.