Depends where you are and who you know, as well as how much land, obviously for a contractor to come out to a small field will be more expensive, to do more acreage at the same time it'll work out cheaper per bale. Also the number of bales per acre really depends on the quality of your grass - we usually get 100 or more bales per acre, but over the road we did a neighbours field which had nil maintenance and got 14, they used to get over 100 when they cut it regularly for hay . OH does ours, and we used to sell our hay at £2 a small bale, and I know in Herefordshire where you can still buy at £2 a bale. So the cost of someone doing it has to be less than that I'd have thought.