I would definitely have in mind something you are ready to buy anyway, a tin of tobacco, or some bulk tobacco.
If possible, since you'll be out of town, I would try to visit twice, a day or two apart. ( I realize you've already
gone and come home, but addressing the question for the future.) The first visit, do a pretty good survey of
potential pipe purchases, buy your tobacco, and use the time to smoke and get to know the owner or staff a
little. And, study the pipes. I really don't recommend buying a pipe in one visit. Really, a week or two is
a better time frame, to find a few you like and think it over. You can have an infatuation with a pipe -- it's
unique, but the luster is fleeting. Someone might buy the pipe you fancy, but I think that's better than buying
a pipe in 30 minutes or an hour or two. If you come back and still like the item, then it's a go. Or you can
have back-ups in mind. Some folks like to do it all in one encounter. That's okay. Not me. You might well
own this thing for forty years or the rest of your life; why rush?