:... ignoring hundreds of "can I help you's"...

Take an afternoon off. Drive over. Spend a few hours pawing through the whitewood 2x4s, looking for vertical grain, not warped, and small knots. Keep the pile neat, too... unlike most of the other customers who paw through it. If the pile is a mess, straighten it while you search. When asked if you need some help, mutter something about carving a Greenland kayak paddle, and you're on a mission to find the perfect wood. Straight, vertical grain, some knots. Be passionate in your explanations. They'll move on quickly.

Given enough time, the entire staff will know you as the benevolent crazy guy who whittles a boat out of wood, and they'll just glance out of the corner of their eye at you when you pass by with nary a word.

Don't ask me how I know.