Currently our AirForce is extremely busy on inducting two new Aircrafts already, the F-15SA will replace the F-15S. The Typhoon is replacing the F-5s. However down the road in 2020 perhaps we will be forced to retire the Tornadoes, so maybe by 2017 or 2018 a 5th generation aircraft (Most likely F-35) deal will be signed. By the. It will become cheaper and more mature.
Currently the Typhoons and F-15SAs serves their role extremelly will, even when Israel eventually induct the F-35s in around 2018 they will be hard pressed to "Match" our capabilities then. And Israel is only getting 25 F-35s then. And with only 100 F-16is and 25 F-15is to face our fleet of 72+ Eurofighters, and 156 F15SAs and 85 Panavia Tornadoes.
The IAF won't throw in other aircrafts at KSA because it simply can't match it.