Actually, I don't think sellers leave ebay. They just open a new account, if they get caught at being unscrupulous or get too many negative feedbacks. There are also others that have back up seperate secondary ebay accounts to shillbid on there own stuff if it is not selling high enough with no reserve. That way they can buy there own item back and resell it. That is what it looks like this seller did.
http://cgi.ebay.com/ws/eBayISAPI.dll...K%3AMEWAX%3AIT They bought this with a seperate different ebay account, then had the nerve to relist it with there same original seller account here for double the price.
http://cgi.ebay.com/ws/eBayISAPI.dll...m=330548008311