When I sell records on here (which is not too often) I generally sell well below dealer 'book price'. People forget that a dealer has overheads (staff, premises, stock, cash flow etc) to account for as well as trying to make a profit. As collectors we dont really have that problem. As a general rule I look at the price guides, look at other sales lists and take a view from there. Usually as a general rule of thumb my sale price works out about 50 -60% of the 'book price'.
However I do agree that I look at the sales pages and say WTF when I see some of the prices asked, particularly for relatively common records. I dont comment on the sales post, but I sometimes wonder where they get the price from as they are somtimes top whack and then some.