Hey Dick,
Not sure where "CT" is but I have replaced the lenses in my two overhead hatches with acrylic from Clear Cut Plastics in Seattle's Fremont district on Leary Way. Bought a couple 1/2 inch thick sheets, 22 x 22 inch and 28 x 28 inch, for $127 with tax. That included a $9 charge for cutting to size.
There is also a new TAP Plastics at the south end of Lake Union across from the Buca di Beppo Italian restaurant. Haven't dealt with them.
Another place that sometimes can help is Laird Plastics in south Seattle, just a little north of Boeing Field. They sell scraps by the pound, but thick acrylic is sometimes hard to come by there. Worth a call, probably.
I think acrylic is considered superior to polycarbonate (Lexan) in these applications because of greater resistance to surface scratches and resistance to discoloration with age. Lexan hates sunlight I think. Acrylic will still crack internally, or craze, as it ages, though.
I used clear acrylic to get more light in the boat. Not sure if I'll regret that later this summer. Hope this helps. If you need more details I can get you phone numbers and addresses.