I ask myself that question all the time. When you make daily purchases with your credit card, you are paying the transaction fees. It's factored into the price. If Walmart/Target/Giant offered a discount for cash, I'd pay cash. They don't; so I use my CC.
Anyhow, did I mention I went to Alden of DC this weekend? The staff is very polite and friendly. I recommend dropping in if you're in the area. They have a cut away shoe which shows the different layers of construction.