Same thing with aircraft. There has been an interplay between aircraft and SAMs since the 60s. When the Israelis first encountered SAMs (Soviet used by the Egyptians) they had a hard time, but then soon adapted and got the upper hand (but not before losing a number of aircraft). Since then it has been a ping-pong match of SAM versus jet, ECM versus ECCM, sensor fusion versus stealth. In the air to air game the missile has become better than the aircraft (unless you are stealthy), and in short-range A2A combat the short-range IR/IIR missile (be it the US AIM-9X, Ruskie Advanced Archer, EU ASRAAM and Iris-T, Israeli Python 4) have all reached a level whereby getting one shot at you within a given range is a guaranteed kill. Especially with every airforce of note getting helmet mounted sights.
Surface to Air missiles are also coming close to that. Their edge against legacy (i.e F-15s, F-16s, MiG-29s, SU-30s, etc) aircraft has gotten to a level whereby having one shot at you is not exactly the best way to have a good day. In the Gulf War SAMs brought down a number of Allied planes, even though we had a lot of ECM and Wild Weasels doing cover, and even though those were SAMs of an older generation.
Which brings the Raptor ....it can manage to engage even evolved SAM systems with an almost guaranteed level of success. Something no other airframe can say. In the fight between sharpened stick and bow and arrow, the F-22 is the bow and arrow. It is far more expensive than any thing else flyng (well, let us not talk about the B-2), but it will do the job better than any of them.
Right now Israel may not need Raptors, but as more and more nations in the region get advanced missile systems (and I am not talking about Tor) then a point will reach that Israel will need to seriously consider advanced aerial weaponry (not necessary the Raptor mind you ....it could be a stealthy UCAV, and several nations are working on that, or a stealthy stand-off cruise missile). And even then it is not to say that Israel would be neutered ....far from it ....just that more of their planes would get shot down.
The Raptor is expensive, but a point is coming when warfare against countries that can get their hands on certain weapons will require it. Whereby the 'options box' for aircraft will either require a dumb bomb truck (for sending low tech Jihadis to meet their virgins) and a high tech Buck Rogers fighter (for meeting enemies that have more technology than your basic Kalashnikov and how to get the camel to walk an extra mile on the same water ration).
(Although there are other considerations to Israel getting Raptors ....for one, there are some who would not be happy with it because Israel has, on the past, been a little ...erm ....'porous' ....with technology, especially to places like China. The second is what you said ...the cost issue. Although if ....and it is A BIG IF ....Israel gets Raptors, you can be certain that it is Uncle Sam who will be meeting most of the costs involved. The only nation that could possibly pay for Raptors, apart from the US, would be Japan. And as things stand, even they are not getting them)
...Israel gets Raptors, you can be certain that it is Uncle Sam who will be meeting most of the costs involved.==
Grab you wallet and you know what to do. Some day Uncle Sam will bankrupt himself.
Russia lets US to spend zillions of money for F-22 fleet then come up with the counter measure which renders them off.
Very simple. F-22 is very seen on the santimeter radio band. Agreed? So if you creates the sensitive reciver antenna then you can have the good radar in santimeter band which will see those F22s as the birds in clear sky. So all zillions of US dollars will go to toilet.