Yup, $600 is pushing it, but I'll bet he could find
something at AC4L and maybe the
AA's from Philharmonic Audio to start. By all accounts they're very good, budget friendly speakers with enough bass that they can be used as mains or moved to surround duty if you fall into some money and want to upgrade.
Like 2 channel said, it's not top shelf, but I wouldn't have a problem owning those speakers (already have that receiver).