Not trying to talk down to you but there is no value in buying the rights to do someone's work... I don't do it but I do see why people buy clients from other companies. But all I see here is a land owner that has some equipment trying to get the best deal he can. In 6 months after he is done paying you only $200/month ($700 he pays for taking care of his properties MINUS $500 you are paying him), he can just walk to another lawn care company.
The value in buying clients from another company is that they had to market, meet with clients, estimate, and sell the service. That is time & money... That is the value of the clients you buy. He did none of this....
Only value in what you are buying is equipment and I do not in any way see 6,000 in equipment from what you posted. I bought a trailer like that used few years ago for $500. Walk behind that size could run 1k-2k. I see almost no value in used hand helds unless they are BARELY used.
B.S. Horticulture (Virginia Tech)