Oh I am sure there are many materials that could be Cheaper. However a number of questions come into play like fire resistance. Being a combat vessel Ford has to be designed to deal with fires.
Overall though this conversation lacks has been based on an assumption. We assume this is more expensive than it needs to be.
Back in 2018 Senator Chuck Grassly pulled the same stunt on a previous Air Force secretary asking why the USAF was looking on spending $10,000 on toilet seat covers. Those seat covers were for the C5M Super Galaxy. They cost that much because they were not a common component. The OEM Lockheed had originally designed them back in the late 1960s and manufacturing for new C5 was long cold. The USAF had ordered replacements about three times by then each very expensive as building the replacements meant they were custom made.
So $10,000.
Of course after that the USAF started making replacements for only $300 because they realized they could 3D print them now.
Basically if Mike Waltz found those sinks cost more than market value he would have the Navy Secretary on the grill after the Air Force’s $90,000 Bag of Bushings.