Pespex window sliders

[sniff petrol]

I'm putting some perspex windows in my 205 GTi and would like to have an opening slider on the drivers and passenger side. I see Demon Tweeks have what I need for £30 each + VAT for item no 80C205 on page 360 in the new catalogue, which seems a bit expensive at £70.50 for 2 small peices of plastic. Are there any alternative supliyers you can think of?

And they don't have to be road or race legal as the car is purely for trackdays.

[CNHSS1]

Airedale Plastics do them too iirc, but dont know prices off hand. think they are in teh blue book, let me know if you cant find them and i will dig it out. not too difficult to make if you are DIY handy.
Other alternative is a round hole in the window and a 'teardrop' shaped piece of window plastic (preferably polycarbonate) mounted with a number plate mounting nut and bolt. very difficult to describe, bit like a cover on a domestic door lock keyhole.
tighten the bolt for a bit of 'stiction' and then the teardrop can be set to cover the hole fully, partially or not at all. like the sliders, they arent big apertures, but enough to gesticulate to marshals and let the steam out of the cabin on a 'hot' lap

[CNHSS1]

http://www.plastics4performance.co.uk/pro_windows_...
found this lot in my favourites, chester area code so bit more local than Airedale