Those Nashbar bags look nice.
Most of my bikes have too short of chain stays to carry square panniers without heel strike.
There are also front panniers, or as mentioned a front basket.
If your panniers are clean and empty, you could probably take them into the store. Load them up in the store, and then empty them at the checkout.
I do that when I'm shopping in Portland with re-usable bags. Just carry the bag around the store until I have what I want, then take it up front, dump it out, check out, then load it up again.