I just did a search on the Internet and came up with numerous situations, particularly when it comes to gas where there are different prices being charged if you pay cash rather than use a credit card, much to the dismay of many customers who want to use their credit card. I just googled credit vs cash prices. Below is one link I got:
http://www.cnn.com/2008/LIVING/personal/07/22/cash.vs.credit/index.html (http://www.cnn.com/2008/LIVING/personal/07/22/cash.vs.credit/index.html)