$900 is horribly overpriced for an inexpensive material like Fiberglass.
I bought a first rate Miata aero kit from Racingbeat.com (RX7 and Miata tuners) and I don't think anyone section was more than $400. And that's from a company with very high quality control standards. Their Fiberglass unlike 99% of that available in aftermarket world usually requires little if any shaping/sanding.
No matter if its from Racingbeat or another quality maker, fiberglass will NEVER fit as well as OEM parts. Polyurethane is made from a mold and probably lazer cut for a fit that rarely deviates more than -1mm. The aftermarket fiberglass really depends on the guy making the piece on that particular day. So its much more time intensive and has the big drawback of being very easy to crack with as little as a -5mph impact. The bodyshop will also charge you their usual steep fees to prep fiberglass so it will nullify any savings vs going with factory parts.
The guy selling the GT3 factory bumper is probably the same guy I got mine from (Dayton @ DPS Motorsports). Anything below $900 is a good price but I doubt he'll be selling many at $500 again, probably a good way to draw attention to his auctions through forums like this one.
here's a great example of fibgerglass with a terrible fit.
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