To the OP, I wouldn't suggest paying over $20pp unless its something you really really want. For example, a bowser, shazam, or even a krak.
One thing I've noticed with zs n ps, is when a new polyp comes out, it's pretty hyped and averages. $50-150pp. Then people start harvesting and the price, most of the time, starts to come to reality and closer to the $20pp range. To each their own though. Some people like to pay the wazoo price just to have that polyp before everyone else.
I like to swoop in when the time is just right.
Remember when those red hornets were running 75-100pp? Yeah look at em noww!