I do my own sunscreens - but not arched windows. Our renter wanted one on a high arched window with southern exposure 6' long and 1.5' high. Ace Hardware and quoted $60 - but the lady seemed confused about price so that may be incorrect. And she said the company they contract with actually cuts slits into the border to make the arched border. I would have to do precise measurements, order and install.
I contacted Imperial and they indicated they had the machine to bend the border, and that the price was $90. And for $35 they would first come out to measure, and then a day or two later come back to install.
Not a bad price for two trips and a quality product that is guaranteed to fit ... and last a long time.