I also want to say that these inflated prices in no way reflect the "literary" quality of those books. Like, at all. The cost only reflects the scarcity and a near-mint condition (at least one hopes). Any good collector must be well aware of this, and proceed accordingly when opening the wallet. Don't expect that dropping 50 bucks on a rare book will get you the reading experience of a lifetime... alas.
Which brings me to these Florence Stevenson (1922-1991) Gothic paperbacks, the virtually impossible to find Kitty Telefair series. According to the much-missed blogger Curt Purcell, this occult series features terrific vintage Sixties and Seventies flavor while engaging in classic horror tropes like vampires, sorcerers, and past lives. Rare and good? Mmm-boy, sounds delicious!
Also impossible to find is any info on Ms. Stevenson herself, which kinda drives me crazy. A few of these titles turn up very occasionally on Abebooks if you have a sharp eye and email alerts—same goes for many of her other Seventies Gothics; I myself only own two of her Eighties horror titles—but these are the kinds of paperbacks for which you must haunt thrift stores, garage sales, and junk heaps, cursed for eternity.