Where's the best place to buy a purebred Turkish van kitten in the United States?

There's only about 6 or 8 breeders in the entire country. Just Google where you live, the breed and TICA, CFA or ACFA. Expect to pay at least $1,000 even for a pet quality kitten and to wait till NEXT Spring or Summer for a kitten.

The "most reputable" breeder you wouldn't be able to afford to buy one from as they'd be the ones with that regularly have Best of Breed season to season.

Why do you want a breed that I'm betting you've never even seen in person?

Check out the CFA and TICA web sites - they have a breeder list on both of them. Most pedigreed cats from reputable breeders have a waiting list - they don't breed many litters a year, and retire the cats after just a few litters. The time on the wait list varies based on what you want - it will take longer to get a show quality cat for instance, and if you have your heart set on a specific color that may take longer. Contact the breeders you get from those web sites, and take it from there! Note of course that you are not going to get a real Turkish Van from Craigslist, the shelter, etc. They are not rare, but still fairly scarce, since Turkey no longer allows them to be taken out of the country without a whole lot of trouble - they have been declared a 'national treasure' and indeed they are :)