Welcome to the forum!
I feel for ya, McGove; I had a Spirit 23 and talkked to the Glasstron folks about a new hatch. It is a plexiglass moulding that they had made locally (Austin Texas). It is not available. I figured the best option would be to make a wood or aluminum frame and use three flat pieces of plexi to duplicate the prismatic shape. Another option would be to make a mold (maybe press the hatch lid into a shallow box of plaster of paris?) , then make one out of fiberglass.. I sold the boat before getting to properly replace it, but I was leaning toward a DIY wooden frame with smoked plexi inserts. A good woodwork shop could probably knock one together for a couple hundred. Diy cost for materials would probably be around 100.
I really liked the Spirit. I sailed it a lot around Lake Pontchartrain and out on the Mississippi Gulf coast.. I had a Honda 7.5 HP engine on it .. outstanding combination.