I posted this for someone looking for a hardtop but it applies to your hatches too.
A old hardtop may not be bargain. My hardtop had to be totally refinished last year. 25 years old. I did it myself but if I had to pay someone it would have been cheaper to have a new one built.
All my hatches have problems. They are on the refinish list this summer. It's not likely what you find will not need refinishing.
The gelcoat gets water underneath and pops it off. The GW substrate is a difficult to bond to material. I sanded mine down, epoxy primed it and used AwlFair epoxy fairing compound. It was then painted with AwlCraft 2000 epoxy paint. Non-skid was applied and additional AwlCraft coats. If there are deep cracks in the substrate they have to be ground out and epoxy repaired. It's a lot of labor and why repairs are likely more than building new. Epoxy repair will outlast polyester by a significant margin.