Skipton's used to carry them but they say they can't get any right now. Saltyunderground dot com claims to have them ready to ship but I have never used these guys before.
Given that the shipping is more than the Berghias in small quantities, I would definitely go in with you guys on a shipment. I have been considering biting the bullet and ordering a few and eating the enormous shipping costs on just three Berghias, but if you are going to order some, I would love to get in on it.
For the record, the Berghias work amazing. And they are 100% going to work unlike other supposed solutions. I used ONE in my old 30g tank and it took about three days before I noticed anything, and then on the fourth day, one aiptasia was gone, and a few days later, everything was gone.
The issue is that the spores can be in the water column and find rock before the new aiptasia can grow. So the berghia starves to death because they don't eat anything else, and they are too small to ever see again once they are in the tank. This means the aiptasia can still reappear months later. The best thing would be to have an aiptasia infested quarantine tank...like 5 gallons...and let the Berghia breed in there so you have a constant supply.