I found this article this morning, and thought it was a good read.
https://aquaboxaquariums.com/media/l...k-vs-dry-rock/
The only part I disagree with is this:
"Since dry rock is, well… dry, the shipping cost is greatly reduced. Transit time doesn’t matter making ground transportation the standard option, and lacking water weight it comes in much lighter loads."
I have weighed dry rock before and after wetting. With Pukani there is about 8% weight difference after several weeks of curing. With Marco and other mined rocks there is almost zero difference - little enough that it is negligible. So if you think you're buying a whole lot less pounds of rock because you're buying dry, forget that.
The shipping cost difference isn't so much in weight, it is in the transit method (live rock must be very fast from ocean to retailer, dry rock can take weeks to get to the retailer, doesn't matter).