Idea: make a network of ebays, with each one specializing in a certain category: cars, collectibles, etc. That way, a community forms around each ebay, and each community can develop its own quirks that make sense/are convenient for that particular ebay, have its own experts (perhaps with karma to differentiate those experts), etc.

Well, I can imagine some differences. A powerseller wants the highest amount of profit, but someone who likes to sell his product asap to someone who is like able to pick it up TODAY has different needs.

I recently had some issues with eBay where I had to relist an item 3 times because of scammers. Why does your item disappear before the deal is DONE? Why not have ME decide when it is sold, and not the buyer?