I've been on
ebay 11 years, with a perfect 100% Feedback of around 2070. I now sell only sets and singles - no large lots, no packets, no bulk (except for discount postage, which is a different animal).
I am lucky I live in a major metro area where CraigsList is HOT. I keep CL full of bulk lots, especially on album pages, in the $10 to $50 range. I don't make a lot of sales, but when I do, it tends to be a repeat buyer who comes back again and again. I also put Commonwealth items on StampBoards, which is free, and occasional lots on Delcampe.
This year, I want to go back to bidStart again, with a different approach, centered around selling individual covers. My main goal in 2013 is (1) to sell $2500 worth of discount postage and put the money into silver, and (2) to clear out the rest of the large lots on album pages, as they take up a lot of room and are almost impossible to sell at auction for decent prices. For 2014, the goal is to cut covers down from 40,000 to 10,000 and picture postcards down from 25,000 to 5,000 favorites. Big goals.

I cannot emphasize enough the importance of converting an
ebay or other auction buyer into a repeat customer, OUTSIDE of
ebay, with no PayPal crap, and a lot more flexibility. What most folks don't realize is that
ebay is the best FREE ADVERTISING in the world. An item displayed for a week, with 12 pictures if necessary, visible to millions of people, with as much description as you care to write, for 50c or so. And you can certainly word a listing to "encourage" people [hint, hint, nudge, nudge

] to contact you privately for more variety and lower prices. That's not difficult.