Hi guest, you will undoubtedly have a wait for a chihuahua, particularly a bitch-they have such small litters and breeders tend to hold onto bitches for that reason. Your best bet would be to get in touch with the breed club, get in touch with some breeders and get on their waiting lists.
BRITISH CHIHUAHUA CLUB. Sec. Mrs C Towler. Tel No: 01322 351961
Hope that helps :)