You might be able to cheap up a window like the PO of my car did.
Looks like they used a good window from a non matching top, and just hog ringed it in place. I've also seen nice heavy gauge clear vinyl material at Jo-Annes. I wonder If it could be epoxied in place of the old window..... cut a section of vinyl larger than the window opening and make a window sandwich..... the PILOBOND adhesive that was suggested to me at Elliot's Hardware has worked great on my top......