What are spoilers made from?

Polyurethane.

Don't get a fiberglass kit (IF there is one for the 03)... they are not flexible and WILL crack when you scrape.

The S body kit pieces are made out of polypropylene as far as I know (I say polypropylene because that's what the Vuteq body kits are made out of, and Vuteq is one of Toyota's OEM manufacturers). I'm not too sure what the spoiler material would be made out of though. Polypropylene, like the rest of the body pieces, is not stiff and rigid. It has some flexible properties so that it does not crack when you accidentally hit something. It's also supposed to have a high resistance to heat (like the heat generated from your engine bay). The spoiler is a different story though. It's not mounted low to the ground or anything, so the possibility of "scraping" is near zero unless you mean scraping it with a box or something while you putting it in the trunk.

The price I quoted you from Fremont Toyota is for the lower body kit pieces only. The spoiler was omitted for good reason; you need to drill holes through the trunk to mount it along with the wiring. That would probably require either Toyota or some other shop to do it. If you want, I can check the pricing for the spoiler and wiring harness if necessary, but installation will be a B**** if you do it at the Toyota dealership. You might be better off finding someone else to do it for you. Cuz if they do it wrong, you're going to have major leakage into your trunk on runny days, or have a stop lamp on the spoiler that doesn't even work. All things to think about... PM me if you want me to check that pricing out for you as well.