What are the LD4B manifold worth?

I had one on a 360 with 318 heads back 22 years ago. It ran great, car was a beast. I found one at a local swap meet for 80$. I agree about the ld4b and ld340 being way overpriced. I'd just get an air gap as well, however if your selling one and people pay 300 then that's what they are worth.