I'm regularly participating with new works at the Bad Apple Artist Collective auctions at the end of every month.
For the auctions, every artist creates a work to a specific imaginative theme which has been voted by the fans of the collective.
To participate a facebook account is required. Bids are placed in the comment section.
Most of the pieces have also a "Buy it Now / BIN" option which can be used by writing "BIN" in your comment.
Anonymous bids can be placed by writing a private message to the Bad Apple Artist Collective Facebook Page.