If you want to try Nina Coombs Pykare, then the most cost-efficient way to get her backlist works is via Fictionwise with the weekend discount coupons, which should take them down to below $3 if a good one is available.
They've got
at least 24 of her titles as DRM-free MultiFormat,
reprinted by Belgrave House, which also does a number of other previously-published reprints, mainly for Regency romance, but also a few other genres including gothics and non-romantic suspense from other authors when last I browsed.
Also, Marion Zimmer Bradley apparently tried her hand at writing gothic romances back in the day. If you are familiar with her sf/fantasy work, you may want to try them for the curiosity value, and they're fairly cheap at $2.99 each (less with coupon).
Castle Terror &
Bluebeard's Daughter
Disclaimer: I have not read any of these myself, although I did buy the MZB books on sale for said curiosity value.