eBay, the online auction marketplace, facilitates somewhere in the range of $50 Billion in gross sales a year. Thats $50,000,000,000 worth of commerce that takes place because of eBay.

Recently, eBay has been making some changes, including changing its rates, eliminating seller feedback, and other various changes. Many sellers, including the power sellers, are not happy with all the changes, nor are they happy with some of the bugs they’ve been seeing because of the changes. There has even been talk of a boycott of eBay and all sort of embattlement accusations between eBay and its sellers.

Which leads me to the question: if not eBay, then what? Who is directly competing with eBay as far as providing an online market place? Craig’s List and Amazon.com both provide marketplaces, but neither of them provide a sufficient online auction system. The closest competitor was Yahoo! Auctions, but that site was taken off-line last year.

Obviously for an auction site to be successful, it would need to have a critical mass of both sellers and buyers, and with eBay around, those sort of sustainable numbers would be hard to achieve. But suppose sellers and buyers decided to leave in droves from eBay to another online auction site. Who is available to take them? Or does eBay have such a monopoly that there is no other alternative. If eBay were to suddenly stop existing, what would happen to that $50B of economy?