You can’t drop the price of cruisers, otherwise you will obsolete AC/ftrs in terms of naval defense.
3 ca @ 10 ipc = 30 ipc, att/def = 9/9
1 ac @ 14 (1/2)
2 ftrs @ 10 (3/4) = 34 ipc, att/def = 7/10
You’d have to drop the price of ac’s to about 10 to even make the ac/ftr combo worth it, or up the defense of acs, but even back at 3 defense (if price stayed at 12-14), I’d still probably go with the cheaper cruiser knowing that I still get the 9 for Att.
Also the bombardment (even if nerfed) is still very valuable, it essesntailly makes a cruiser a ftr for any coastal territory and for the UK that is gold. Sz 12, 7, 6, 5 are all frequented by the UK and combined touch like 9 territories. That is a lot of uses. You also don’t have to worry about AA guns.
I also don’t think you can drop the price of BBs without obsoleting another naval unit. Either the cruiser or ac/ftr combo will be phased out. Unless the CA is so cheap it makes BBs pointless and if that is the case then DDs become useless. In order to make an 18 BB, you’d need a 10 ipc cruiser but I think that just messes everything up, you’d have to drop the price of acs, ftrs and dds and then we are back to the same spot.
At some point you have to realize that navies only serve 1 purpose, to get land units from A to B. So navies will always be the bare minimum needed to protect your trns.
You could make ships as cheap as possible but if there is no threat to your fleet they still won’t get built. (exception - trns)