I bought my puppy from Edmund Kennels last year (April). I wish I had known that you ought to leave a puppy with its siblings and mom until 12 weeks old. Instead, Jean sold to us when our little pup was only six weeks old. She also mentioned that she had taken her from her mom the week before. The Vet we took Dylan to later was really shocked.
The Vet mentioned that Dylan would not be like a regular Westie, because she would be more bonded because of her young age. It's difficult to tell that.
I suggest checking this site out first: The West Highland White Terrier Club of America
www.westieclubamerica.com. They even had a test to check on your fitness as an owner.
But because when we got there we found out that they had Yorkies, and Cockapoos too, so you may be more interested in those breeds, I would still recommend checking out those dogs websites first.
I love our puppy to pieces, but I was concerned when Jean discouraged me from seeing Dylan's mom, told me that the puppy had never walked on grass as well as the lack of groomer info. Which we would find out, they need grooming approximately every six weeks. They also are VERY prone to skin allergies (watch for a lot of licking of feet which discolors their feet too).
I hope this helps, good luck in your search!