
I would contact the breed club for the breed, Go to the Kennel Club website http://www.the-kennel-club.org.uk then click on breed standards, Toy, Chihuaua. Read the standard so that you know what the requirements and size are for a decent one (if your looking for naything else don't bother as you will end up with a poor sickly mite). At the bottom of the page are the club deatails.#
Contact the secreataries and find out if they know anything about the breeder you have contacted, and ask what the normal price range is. IOf they don't know of teh breeder or worse know they are not reputqable, then get on a waiting list with a decent breeder. Ypou will probably have to wait quite some time, as they have small litters so you will be waiting for a pup surplus to the breders own requirements.
It will be worth waiting for a typical well bred specimin where health and temperament matter. Sometimes you may have more luck purchasing an older pup or adult that ahsn't wuite come up to expectations for the showring (if you want a pet then this will be fine).