"Free"? Only if you don't count the cost of the fuel you'll burn reducing the sap down to syrup or assign any value to your time. There also is the cost of the taps, buckets, and other gear in the process which aren't expensive but not free either. The process of making the syrup from sap takes many many hours. It takes about 40 parts sap to make 1 part syrup. I suppose you could do it over a wood fire outdoors but that's harder to control and you still need a large supply of wood.
He's retired, he's had the gear for years, and he's got tons of wood from dead-falls.