You may not see, and I don't have anything to say you are wrong. That is the reason I said if Sony want to do it. They could even go crazy and sell for 99 while costing 149 if they see it as a way to tail it out if PS5 is BC and just capture some late buyers on the platform to get PS+ revenue.
Its kinda possible. But......
The essentials are APU/RAM/HDD/BRD/Controller. Now at best (and this is being very optimistic) it cost them like $20 fr each f those components. Thats already $100 right there and you have not factored in other things like cooling/assembly/packaging/cables/PSU/PCB/Supporting chips and memory.......etc.
And remember, that $100 is being extremely generous because the APU/RAM/BRD/BRD all cost n less than around $25 each. Definitely not $20.
Best they can do if they really want to butcher the system is take out the HDD and put in like 256GB emmc nand flash drive (and the cheap slow kind) and d away with the disc drive. Maybe then they can get it to $99.