Ditto to CJ & Jamie's replies.
I think most items are less expensive/more readily available in the US

.
Here, I shop at Leo's & Beau, too, plus a little Mom & Pop store in Delta (minutes away from the border) called Photo Expert (photoexpert.com). If you go on the weekend, make sure that you hit Leo's early (sooooo busy on Sat), and Beau isn't open on weekends.
Have fun on your trip!