I'm sure I leave money on the table but my time has value and I am not always willing to wait forever to get the perfectly lowest price. I recently was shopping for a set of Campy Record brake levers. I wanted them to be correct for 1972. I found 3 or 4 examples on Ebay, one perfect, the others with various pros and cons. I looked at sold listings but as usual there aren't that many examples for exactly what I am looking for. So I start watching the auctions. On the first set up (not the perfect set) I put in what I think is a reasonable bid. I lose but the end price adds a data point. The second set is the perfect set and I have a pretty good idea what I am willing to pay (which is actually well above what I think the real market price is because they are perfect for my project). So I bid and sit back and wait and I win.

The point is that as I am going through auctions with various pluses and minuses against what I would consider perfect my view of the price I am going to have to pay to get what I want within a reasonable amount of time (I am usually willing to wait weeks, not months for a project part) changes. If I've lost three auctions by bidding what I thought was reasonable then my idea of reasonable is not really reasonable for the time frame in which I want the part. My view of reasonable has to go up or I have to wait longer which is no guarantee that prices will go down or that the perfect part will come along in any reasonable time.

Actually in the end I usually end up buying a lot of stuff from buy it now or make offer listings. I follow buy it nows and by the 3rd or 4th listing they might get down to a reasonable price. I will often then make an offer (even if it isn't a make offer). What can I lose? If it is a make offer listing I always make a pretty low offer and see where it goes. Sometimes I get lucky and sometimes I end up paying close to the buy it now. If a seller gets offended by a low offer then forget them.