madmantr,
If you buy sap, you work out a deal with someone interested in selling sap. I purchase from several sources. I purchase all the sap from some of them and only what the others cannot boil themselves. I pay the prices that were listed in the maple syrup digest for fresh sap delivered to my sugar house. Sometimes someone comes with 50 gallons and sometimes with 1200 gallons. I keep a running tabulation of sap delivered and pay at the end of season. If someone wants cash at time of delivery, I pay slightly less. Since maple is my main source of revenue, my checking account can be getting kind of thin at this time of year.