Commercial sprayers that work off of a tractor's PTO (power take off) can cost $500 or more. I cobbled this one together for around $75. It involves a small pump that attaches to the PTO. All the connections and hoses are items found in any hardware store. The 55-gallon drum is a piece of salvage.
Actually, the sprayer is more powerful than I need. I'm considering taking it to the farm auction to see what I can get for it. I have down-sized plans for my fruit trees. After all, how many bushels of apples and pears do we need?