i had a brainwave!, maybe this has already been thought of...
why doesn't somebody set up a cover project store on ebay?, list a load of different covers for $1 each, (when i do a search i usually select to order the results by cheapest first), then inside the listing put something like, "if you REALLY dont want to spend a dollar on this, all covers are available for FREE on thecoverproject.net"
the people selling won't/can't list at those prices, so they would loose sales, the people looking would probably not buy and come straight here!, the downside is some people would probably still want to buy them...