After my morning workouts I basically always get a protein shake at the club's bistro. I get one with strawberry powder, strawberries, and peanut butter. It ends up being rather tasty. The price of one of these shakes is a fairly disturbing $6.60. However, I provide my own protein powder, so they only charge me half price. The packets of powder are available a few feet down the hall for $2.00. By buying the packet in one location and taking it to another location I save $1.30 per shake.
It makes me wonder if this business model is intentional, or the pricing just wasn't thought through very well. It's possible that this works so that people who are price-conscious can get a shake for a slightly more reasonable $5.30, but the majority of people won't be willing to go to the effort (or even find out that such a deal is available), so most people will still give them $6.60. Or, maybe 50% off is a really easy thing for their system to do and they don't care or realize that there's a price discrepancy.