Are expensive putters worth it? Yes and no.
I have been collecting putters for 40 years. I also make/modify putters. I have at least 100 putters - it's a disease. As luck would have it, I invented a putter shaft, which I am patenting. While I await the gifted ones at the USPTO to take action, I decided to manufacture and sell putters. Some time this year I will be selling putters. They will be VERY expensive. Are they worth it? You betcha.
Having said that, I would never pay $100 for a putter. Why? Because I'm cheap, I don't have a whole lot of money, and putters are just weighted sticks. I estimate there are 60,000,000 putters in the world. Surely you can find one that works that somebody will sell you for under $100. However, a putter that "works" is worth a lot of money.