There are sometimes significant differences between increased price because more ressources are required and icrease prices for the sake oftaining more moneyobr.
Reason these cost so much,
1) The industries involved want to make profit.
2) Lack of competent enought scientists and engineers.
S-300 missile can hit targets at Mach-8 at longer range, yet is far cheaper than "patriot" missile that can barely hit SCUD missiles.
Hmmm...
Companies want to make a profit. Of course no manufacturer made a penny during WW II.
Who would have thought.
The simple fact is that modern weapons use materials that are hellishly expensive, require ASSEMBLERS in some cases to have advanced degrees, and represent a complexity found nowhere else in modern society. A WW II era tank was steel, hardened steel in places, but generally the exact same material that is found in everything from cars to wheel barrows. A modern MBT is made from an exotic mix of polymers, alloys, and God knows what else (the actual composition and construction technique is a closely held secret).
Any reasonably competent machinist could, in 1942, have milled any part of the aircraft, ships, armored vehicles, and personal weapon used by any combatant in WW II (even the A-bomb, once the design had been completed, required little more than a set of blueprints and the expertice of a jeweler to replicate). Today's systems are so difficult to construct thet certain skills are possessed by individuals numbered in the low hundreds, WORLD WIDE.
Systems are vastly more expensive (and effective) than their WW II counterparts because they are vastly more difficult to construct out of materials so exotic that they are close to science fiction.
Regarding the Patriot:
The S-300 is, apparently, an excellent system, although it is far from combat tested. The Patriot systems in the 1991 Gulf War were never designed as Theater Ballistic Missile Defense systems. That they did as well as occurred was well beyond initial design parameters. As far as consistent intercepts of a Mach-8 target, there are some
claims by Russian officials that the
S-400 system can perform such intercepts. They are exactly that, claims, with no verifiable documentation. It is entirely possible that they are true, it is also possible that they are complete BS and the system can't achieve this level of performance OR that it has much higher performance. The same can be said for the latest deployed variant of the Patriot.