That is very young to be taking him away from his mother. Why are they selling them so young? Are they even weaned? Many Yorkshire Terrier breeders will not let their puppies go until they are at least 3-4 months old.
Some states have laws saying how old the puppy has to be before it can be legally sold. Sadly some of those laws allow as young as 6-7 weeks but most are over 8 weeks. I found a table of state laws but AL was not listed:
http://www.animallaw.info/articles/o...ysaletable.htm
Is there any way you can get them to keep the puppy for at least a couple more weeks? Even after they are weaned they learn behavior from their mother. Knowing what a baby I got at 10 weeks, I would be afraid to have one younger away from their mother. If you do bring this baby home this young -- definately have the Nutrical ready and buy one of those little heartbeat pillows. Good luck to you both.