It is quite simple..Egypt didn't buy any weapon systems from its budget for the last 25 years or so, it was using the $1.3 billion of US military aid for procurements from the US.. So some part of the $5 billion budget was saved all this time..let say just $1 billion a year.. that makes it $25 billion in the last 25 years and this is a minimum.. That is why Egypt can afford still more advanced weapons that this recent deals.. there are SU-35s in the pipeline as well as another Fremm frigate, some (at least)12 more Rafale, 2 more Gowind corvettes, S-400 and much more..