I'm coming from the thought that you can avoid duties with NAFTA, but you're still going to get nailed with a very large amount of taxes. I got hit with close to $90 on one pair.
This is a completely personal opinion, but I wouldn't want several pairs from the same company. Anytime I've sought out to satisfy my OCD by buying a bunch of T-Shirts (or what have you) from one place I've regretted the lack of variety. Just something to consider.