A little off topic, but as a buyer it really seems that a very large percentage of sellers who had cd/vinyl/music related dvds set price stores have shifted to Discogs. Most the main people I used to buy from have shifted. Ebay has a huge advantage as a buyer in that it's possible to view the actual item for sale. The massive disadvantage is that free listings (as opposed to  the fee based listings of the [distant] past) means that everyone has to navigate an ocean of over-priced items and junk to find interesting stuff.  My take on your question is that for generic mass produced reissues and stuff, a store is good, but for graded interesting stuff with limited supply out there regular listings are fine. I've seen people do well with vice-versa tho.