The more you pay, the less the fun of buying ?

I copied above graph from Seth Godin's blog. He called this 'Joy/cash curve', and explains:

"It seems that for many products, the more you pay, the less fun the buying is. (Not the shopping, the buying). It used to be true at the bottom end of the scale too - the less you pay, the less fun".

We can all argue what the shape of this curve should be in our real life, but the essence of the message is the same. In his blog, Seth can always find the chemistry between human nature and marketing from everyday experience, which most of us don't see them through at all.