These are apparently searchable, and can even be bought normally on the Auction Houses. The exception is that dropped 2.0 Legendaries are BOA, so despite the ability to buy them, you won't be able to send them to your stash, while the seller still gets to keep the gold. Crafted Legendaries can be bought and sold normally though as they are not considered BOA.

EDIT: No longer relevant with hotfix.

Good warning. Thanks for posting.

I decided to move this topic because it's not really forum news. I also stickied it for the time being.

Blizzard has fixed this issue. All BoA Legs can not be sent to stash after being purchased from the AH, but no more can be posted since the hotfix.

Locking thread for out of date information.