The OP made it very clear. He's not looking for a cover. He's looking for the lid.
I stand corrected... thx bubbles
I found this on amazon... LIDS, just have to match the hinge type to what you currently have.
Can you live with it taped? I would bet you would get a good seal with a piece of GORILLA tape on it. I have had Gorilla tape on for a year and more and had to pull it off with pliers to get it to come off. Not sure though about the heat from the sun and what that would do to the tape glue.
AND... you could use the Maxxair vent cover to cover the broken lid and have AIR FLOW with the lid open even if it is raining...
Since discovering MAXXAIR vent covers, I would never just have just a vent lid anymore.
You just have to think about which direction the cover opening is pointing... into or against the direction of travel while motoring.
I hope this helps you better than my previous post... sometimes you read what is not there.