This magazine quotes the cost of a single discharge of 13 inch gun ammunition as 500 US 1904 dollars. No wonder the Navy rarely did target practice!  To put some perspective on that, the entire navy had a 1,000,000 dollar training budget for the entirety of the fleet.  177 ships. That was for all calibres and torpedos.

Besides a neat article on submarines, and other fascinating reading... https://books.google.com/books?id=oqUPv2vzex0C&pg=PA537&lpg=PA537&dq=how+much+did+13+inch+gun+shell+cost&source=bl&ots=L_vfKTUXsT&sig=ACfU3U3H-E...

https://www.history.navy.mil/research/histories/ship-histories/us-ship-force-levels.html#1904

a full broadside must have been rare indeed...