Yes you can still buy it, but the legal status of Amithlon has been questioned by one of the main authors and according to a clause in his software contract, he has withdrawn his IP from Amithlon. Thus according to him, any sales after he invoked that clause are in breach of contract and thus illegal.
Of course all of the information surrounding this dispute can be found on
www.amithlon.net and also on the Amithlon mailing list archives. This doesn't need to be re-hashed here
The problem is this needs to be settled by a court of law, and no one is ponying up the money to do it. An out-of-court mediation attempt also failed.
There have been promises by the other author of Amithlon to release an update, but so far that has not materialized.