PAY WHAT YOU FEEL
Just like it says. It's not a scam. You determine the value.
This is a question that is difficult to answer succinctly (I have written and deleted 4 drafts so far), but simply put, this pricing/payment strategy is there to put the value of the photos I make into my customers hands directly. Art is only worth what someone is willing to pay. I would like to be paid, but that's up to you!
You determine the worth of my work. Whatever decision you make... it's the right one.
ONE SMALL CAVEAT
If you want a photography session that is longer than an hour, I will likely ask you to sign a contract. Legally, I need to be a paid service provider to have a valid contract. So I ask for $100 as a retainer. Then the transaction is complete, it validates the contract and gives me just a bit of "walking around money" as my Grandma used to say.
Sorry if I misled, or pissed anyone off with that $100 wrench!