Maybe I am misunderstanding... His business is just the equipment and the rights to do 7 houses he owns? So for 6k you are getting a trailer, used walk behind, and some used hand helds?
For 2k -3k I could get that equipment or better and do $100 in advertising in the Spring and probably have a bigger business then what you are buying... I just don't understand how he thinks he can "Sell" the rights to mow his houses for some serous cash. I would just offer him cash for equipment and give him a price on his lawn care, not buy the rights to mow his properties from him.