I used to go to our local gun show as a vendor so I could sell off some left over inventory (most of it substantially below my cost, by the way) and had the wife hold down the booth when things were slow so I could do a little shopping of my own. Once I found a dealer selling reloaded .38 special a few dollars cheaper than Wallys sold new ammo for and I picked up a few boxes.
I had been back to my table just a few minutes when the ammo guy showed up and pushed a few dollars into my hand.
He explained that he had noticed my vendors badge and would have given me a discount, but didn't want to let his regular cash customers know that they were paying a little more.
I was surprised because I was happy with the price at the time and had the guy not refunded the difference, I still would have been happy.
I haven't found anyone selling reloads cheaper than Wallys since then, but I did appreciate that vendor's business model at the time.