WrestlingIt seems like Dr. T is being really round about when answering. You cannot purchase these because even the people who ordered these in May have not recieved their sets yet. They will not even be out of production until January (maybe) so I have little doubt of there being another drop before then.
Once they do ship there is a chance that someone might be selling their set privately at a market, either at reddit.com/r/mechmarket or on geekhack, but I wouldn't bet on being able to buy a new set or seeing another drop for while as the original purchaser's have not received their sets yet.
There was an option to cancel purchases after the second delay so drop MIGHT be selling sets that were produced for canceled orders.