WTB: Cheap 58 -60 cm cross bike

I'm looking for a cyclocross bike for my son. Not race quality... he'll mostly ride it on the road, but wants to be able to hit a trail now and then. He's 6'3", so I'm guessing a 58 to a 60 cm bike would work.

He'd love to only spend $300, but hopes he can at least find something for $500 or less.

I know. Not a lot out there in that price range, but I thought I'd see what you might have.

Thanks!