I would say that on a smaller piece of equipment like an aerator you can easily bury the cost and mark it up if you do multiple clients. If you are renting bigger pieces of equipment it may not make things cost effective for you if you are starting the job -$300-$400 a day before you started. Maybe you are leaving money on the table by not marking it up but if you lose jobs because of it you left money there too. I would still get an hourly rate for picking it up and dropping it off factored in. I wouldn't have a significant mark up on the machine, just to stay competitive. Maybe I'm wrong, but that's why I don't rent. If someone wants me to do skid steer work I am at $500 a day for the man and the machine, plus materials(marked up) and plus laborer's if needed. If it's a job on a property you are already servicing I guess you don't have to be as competitive.