It's not a breed recognized by the AKC so they will not have a listing of breeders. I found one on the Lancashire Heeler Webring page:
Carol Tin-tot - Columbia, MO12/16/99
573/446-0828
One of the UK links said for
Lancashire Heelers in the USA to contact:
Mrs J Hoestery at [email]jayne@lancashireheelersusa.com[/email]. She is probably your best bet as her website (above) states that it is a rare breed in the US, but gaining in popularity, and she probably knows other breeders.
Good luck.