|Douglas Muir 406|
I am playing a necromancer, and I wanted to be able to raise people as vampires potentially.
Paizo's designers very deliberately made this impossible by normal means, because otherwise you'd have munchkin minimaxers turning themselves into vampires. Free feats, crazy stat bonuses, +2 CR!
In-game, there are only three RAW ways to turn yourself into a vampire: (1) have someone kill you, then use a Wish on your corpse. A Miracle from an evil deity might do the job too -- I'd allow it, myself -- but RAW does *not* say that a Wish can transform you to a vampire without you dying first. (2) Be a cultist or demoniac of Zura, as noted a couple of posts up. (3) Get bit.
If you want to raise your own vampires, the same rules apply. The simplest way under RAW is to find a vampire. Failing that, you can create your own starter vampire with a fresh corpse and a Wish. Note that in neither of these cases is the vampire automatically under your control.
Outside of RAW, I agree that it should be possible to cobble together some sort of evil ritual using the Ritual rules. It might cost less than a Wish, and if your DM is generous it might even give you (some) control over your new vampire pal. On the other hand, it might require weird ingredients, difficult-to-obtain sacrifices, and really high skill checks. And of course there might be nasty side effects, especially if it fails.