When I was a child, I read a number of Alfred Hitchcock's anthologies. One of them included a short story involving a man with a rare blood type who answers an advertisement for people paying for his blood type. I remember that he had a short aside about how people would criticize him for asking for payment, but that he felt that he should be compensated for his time and inconvenience, particularly since most blood donation places would just turn around and sell the blood to the patients who needed it. Anyhow, partway through the donation, he comes to a realization that the man he is providing the donation to is, in fact, a vampire, and one with a genetic condition that means that he can only drink rare blood types. I remember the narrator was disabused of a few traditional bits of vampire folklore by the vampire; I particularly remember the vampire claiming that the whole "catches fire in sunlight" thing was more along the lines of a really bad sunburn, raising blisters upon contact. At the end, the narrator agreed to come back for more donations. I remember the story's illustration involved an IV bag of blood with a vampire's face imposed upon it.
When I was last home, I looked through Witch's Brew and Spellbinders in Suspense (although I am told that this may have been a generic name for several of his collections) and did not find the story in them. I was fairly certain that we had a third book, but I could not find it in the time I had. Based on eliminating the anthologies that I did browse at home, it might have been in a volume that included two other stories. One involved a crystal bell that could bring people back to the life in exchange for the loss of another's life (initially, the bell didn't work, but someone realized that they had the clapper on their necklace) which ended with someone falling on the bell and having a shard pierce their heart. The other about a man who somehow bought two "knacks", in his case the ability to compose rhymes at any time (and, in fact, he couldn't stop rhyming) and the ability to "make money" which translated to him doodling out perfectly detailed dollar bills whenever his thoughts drifted. Faced with legal problems from accidentally counterfeiting, and his wife becoming increasingly annoyed at the rhyming, he somehow exchanged the gift of "making money" for the gift of silence, and started working for a greeting card company. I do believe those two stories were in the same anthology, but I am not 100% certain that it was with the same one as the vampire and the blood donor.