Complain to Ebay, it's against their policies for members to trade 'on the side'....at least you can get the seller removed/restricted as part of your venting :-)
The least the seller could do is contact the current winning bidder and say "i've been offered $XX, can you match it? otherwise i'll need to end the auction" as some form of courtesy.
As for ebays fees always on the rise, their latest move to encourage sellers NOT to charge for postage is a real ball-tearer.
They will actually take the postage fee out of your account *IF* you continue to charge postage on items you sell....They say offering free postage encourages more people to buy...Pfft!!
Hopefully ACCC will jump on this and cancel it, but the concept is only a week old, so probably a few months before they get canned again.
Ho Hum...