Do you want to let anyone sell their art (I have a Deviantart account and think I am alright) or do will the auctions be sanctioned and selective? Of course patronage has to be selective but who can hold auctions?
Any given artist is free to sell their art and self-represent themselves. If they are already working with a given dealer, the dealer can sell the art or ArtBlock can simply connect the involved entities. With auctions there can be independent auctions at any given time, but we will also be sponsoring events in typical auction house fashion (say a seasonal contemporary sale) where we would be involved in PR and garnering interest from appropriate buyers.