As previously mentioned, call any builder supply, metal roofing/panels place, etc. near you and ask about miscuts, orders not picked up, that kind of thing. You can save a lot of money that way. Everything may not match color wise, you may have to do some cutting, but it's certainly worth it. I understand your want to do clear poly, but I'd do all metal if I could, but even if you end up with some of both, it'll still be a good deal.