No Vamps in CAS sadly, Vampires will spawn whenever you start a new game in SV/RV/BB etc. They are sometimes just the existing townies but just turned.
I've noticed that some people on the exchange (probably the ones with mods that can force CAS open in-game to save Sims) are actually able to upload vampires as character files, so they can be downloaded into the Sim Bin. Does anyone know if it would be safe to download one and completely remodel it in CAS, keeping the vampirism? It seems like an easy way to make your own vampires, but I'm not sure how CAS would handle it. I'm taking the fact that the Sim Upload area on the EA site has a subsection for vampires as a good sign.
@Esther, if you're worried about finding vampires to turn you in Sunset Valley and don't want to wait for them to spawn, I'm sure you could start playing one in Bridgeport, save the household and put it down in Sunset Valley.