E marked glass only at a cracking
price from Uncle Melvyn..
If you are not bothered about the ineffectual heated version visit your local Agricultural machine suppliers and they will put you in touch with the supplier and fitter of laminated screens for tractors, JCB's et al.
You will be surprised at the cost but you will need to provide the new seals and windscreen if you fret about ingress of h2o ie you put your roof up

.