Are you insane?!
Are you saying that Saudi Arabia is one of them? Or that all those oil-rich Arab states are so poor, that they need American military aid to run their entire their respective military? Although, Yemen could be another case.
You do realize that the Middle East is a huge market for US weapons manufacturers? In fact to some extent, they are forced to buy American equipment. The weapons manufacturing sector is one of the few viable export oriented industries in the US. And with today's economic climate, it'll gonna stay that way for a long time. The Americans will push it no matter what. Otherwise, they'll gradually lag behind in technology development. There are many other countries like Russia and increasingly China who make weapons.
Pakistan bought much of its F-16s with hard cash. During the sanctions, some were never delivered and the money was never returned. The same thing happened to Iran when it ordered a large number of F-16s before the revolution. Did you know that the F-14 program was partly funded by the Shah of Iran? And they paid for those very F-14s with hard cash.
Hope you understand my point.