360 Spider - Aftermarket rear screen ?

[GT2man-2]

The rear screen of my 360 Spider is slightly distorted (I guess being in roof down + over a hot engine has taken it's toll).. so I called Graypaul Ferrari to see how much a new one costs.. (are you sitting down ?)

£900 + VAT

Farkin heck !!!

So.. considering they just unzip + zip back in again, does anyone know of a company making aftermarket versions, or should I get into business knocking them out for £400 each ? Heck, they can only cost £20 to make, tops.