About time I updated everyone on how the purchase worked out... sorry for taking so long.
As the site mentions, they're backordered by about eight weeks. It's an accurate prediction, too... we got an email stating that they were shipping the Bergs almost exactly two months after ordering. No crazy, out-of-the blue shipping costs, either; everything was up front.
Our nudibranchs arrived in good condition, better coloured than the ones I ordered from Salty Underground for my last tank. (brown is healthy, white is starving to death). They disappeared into my tank; it took me a little while to be sure, but the aipstasia population is unquestionably declining, particularly in the area I first released them. Probably, given the size of the tank (120g), I should have ordered a few more, but nine adults plus the bonus juvenile seems to have been enough to breed and continue taking down the aiptasia population. I expect to be completely aiptasia free in another month or two.
Here's the site again, for those who are wondering why this necrotic thread suddenly came back to life:
http://www.berghia.net/marketprice.html