Insurance costs have changed a few times over the years. Years ago I believe it only looked at regular mineral prices so t2 ships wouldn’t insure for much, but now the insurance will look at moon materials but it also discounts them by a bunch. The moon mats insure but it’s at a pretty big discount, there’s also profit for each stage of refining the moon mats to t2 build components to look at, so there will be a bit more difference between price of building and raw materials. For t3 ships The t3 components also have some value in the insurance system but that is even more discounted. When t3d came out you could insure them for near full value
Looking at the vexor and it’s variants there’s a tiny difference between the vexor and the VNI, Then there is a pretty big difference on the ishtar thanks to all the moon mats, although it’s still way below what it costs to build/buy an ishtar (currently ~300mil in jita).