I believe forum members have asked the British agent of Niewiadow Trailers -
Freedom Caravans - for a price of a new window and decided not to buy due to its high cost.
They list a
rear* kitchen window for some models at GBP230 with UK delivery and VAT (sales tax), so that's about $CAN 385 before the international shipping is added. You should be able to buy it without the (20%) sales tax but small companies that are not familiar with international sales usually find that very difficult.
* In addition to getting different names here, the trailers have the body mounted backwards to put the door on the British kerb/curb side - so I'm guessing that your front window is the smaller one (87 x 60 cm, 34.3 x 23.6in) that Freedom UK call a rear window. If it is the big one (British front, so presumably Canadian rear - 120 x 54cm, 47.3 x 21.3in) that is a whopping GBP395 or $CAN 660!