I have a fetish about getting a copy that was printed in the original publication year. So I always have a hard time getting an inexpensive copy.
I did, however, get my copy for about $50 USD and I think I got it from a Danish bookseller. It is hard cover, 1964 edition, with a reasonable dust jacket.
The one that was toughest to find was Olga Romanov - Russia's Last Grand Duchess by Patricia Phenix. I had to get a 1999 paperback which is not in great shape, but at least I didn't pay a lot for it. It is ex-library, but I don't think it was read much, so aside from being a little soft and brown around the edges, it is all right. I don't remember what I paid, but I have seen it for as much a $200 USD. And that is just crazy.