there's a guy at my work asking me fore something similar. It seems the days of $100 minibikes are gone, In the past year I've not seen one under 500 that wasn't wholly trashed.
You can pick up a rigid minibike with basically those harbor freight predator motors around 500 new though. Probably a good option for bopping around your property.
Honestly those honda clones like papa posted are pretty decent, they're not gonna last hundreds of hours but they're cheap and suspension and brakes are very good for the price.
Personally I'd be getting cheap old trash and making it work cuz that's fun and cheaper but it doesn't sound like what you're looking for.