The Costco effect

The Costco effect? How about this? We bought a gasser for our current coach because of Costco gas prices. Not only is the gas cheaper, but they only allow accessing the pumps from one direction. Costco gas attendants have told me that local prices are researched essentially daily and then Costco sells theirs for just under that. Typically this results in ridiculously long lines, so we actually try to find good RV parks near Costco gas stations that I can access first thing in the morning. The single Costco we've visited that offered diesel (central Bakersfield) had it on only one island, which also had gas. That island had the longest waiting line of all. (And finally, if traveling the Central Valley of California, I have never found long lines at the Costco on Panama in Bakersfield or in Woodland.)