Bulk selling
5 years ago I started selling my nephew's collection of over 180,000 cards. (all sports and non-sport from the 40s to 2012) He paid close to $20K for them per his notes. For months I tried selling it as one unit or just one sport. Best offer as $450.00 Then I started selling a card(s) or set at a time now still have 150,000 of them but close to $6500.00 for my brother.
Why commons so high?
Most sellers online or shops do not list commons as it is not worth their time (per them) So it is harder to find a fair price for them and if you do they are price them high. Even hard to find commons at shows now days. I think we all have paid more for a common then what we think they are worth. Just to finish out a set or group. We paid for it so we put it in.
Why are the prices here out of line?
You can use several reasons: Some members used to put in what they wanted for their cards. Others find the prices on E-bay and other sites that has fees added into them, a few just used the higher sales. (Why I do not know) Some add in the postage paid. Some have been added a long time ago so the prices reflex the hype or when they when 1st released. Some cards have one real high price and a few normal price so the Median is odd.