It is a way to measure if something is really expensive. Another way to look at it is that $90 is about a regular night out. The choice is between investing 1

It is a way to measure if something is really expensive. Another way to look at it is that $90 is about a regular night out. The choice is between investing 1 evening of your time to save for 1 night out later, or instead invest nothing but lose one night out that you need to spend in front of the TV. YMMV, but probably the tipping point in GP specific situation is that he also had to post them all by himself, which is a huge pain and is probably alone worth it to have amazon do it.