My buddy was running the warehouse at Sears, told me of a one time use mower in scratch&dent. The lady used it, didn't like it and brought it back, 18HP with 42" cut. I gave $250 for it. Chef's daddy has nothing on me. It's been purring for a decade. I also have about an acre to cut.
Go to the hardware store and get an abrasion wheel for your drill, about $5, clean the deck and put a coat of paint on it every other year. It will last forever. You can sharpen your blades, just make sure they're balanced when you're done.