Okay, my idea having seen people's comments...
Something like this: eBid's May Madness!
Participating sellers offer a free gift with every purchase during May (this can be much cheaper than offering a discount, it can be as simple as a sweetie from a tin, to an extra "whateveritisyousell".
) It lasts the whole of May to allow plenty of time for promotion and exposure. It's that far away to give us time to form a detailed plan and try to get eBid on-board, and to produce and promote things like Magz' video.
If eBid agreed to join in it could be promoted on the front page and other official routes. And they could even go as far as offering another freebie to any buyer who buys, say, five separate May Madness items from different sellers. A cap or something.
Sellers taking part put May Madness in their participating titles (means it doesn't have to apply to all listings if you don't want it to). Listings have to spell out what the freebie is. Sellers could also offer a "buy five from me and get XYZ additional gift".
Comments, please?