i would figure around $10-12 an hour. with maybe a 3-4 hour minimum to ensure i gave him $40-50, but anymore than this and i would do it myself.
I would assume this is just someone looking to make a couple bucks, not someone with a licensed/bonded lawncare business or any overhead, so I definately wouldn't want to pay him the same as i would someone who is licensed/bonded, if he damages your house or gets hurt your on the hook. with that kind of gamble I want things cheap.
Paul