As it turns out, I found someone selling a mooring here. And yes, the price
probably does vary a lot by location. In Milwaukee, the only anchorages
protected enough to moor are within the city breakwater. So, there is a registry of private mooring equipment
. I understand some do drop their own equipment without registering.
So, the answer is: less than $1000 for a mooring here, more than $100,000 for a mooring on Catalina Island