I have a gravely zt hd 60. I use it to mow my 8 acres every two weeks. Probably more like 6 acres with my long drive way and various structures on the property. I am on year two of using the machine and have done nothing but oil changes, blades, fuel and air filter. I found it used for $3500 with 30 hours on it. It is a little rough riding especially when you're on it for 4 hours but its a solid machine.