I just ordered some from Alibris.com. I got new 6th editions of Vol 1 and 3 for only ~$32 each. I bought a new copy of 5th edition Vol 2 which wasn’t available in 6th edition.

I wouldn’t pay the exorbitant prices. I think that some sellers look on amazon, see that it’s not available and see if any suckers will pay the ridiculous price. as soon as someone puts it up for a real price, that price disappears. i think it’s a bad scam.  In any case, there are many places online to look for a book…