@Francois - At the moment, you can only add and administer auctions if you're an admin on the blog (minimum level 8).

We considered opening it up, but if you reduce the level people will be able to amend and delete each other's auctions and mess with their bids. In order to do it properly we'd need to assign an "owner" to each auction .. hmm .. I'll add it to our "requested features" list so we can think about it properly and work through all the possibilities.