and @Abii
Actually 4 millions visit, but that's not my point. I said there is the 'potential', and yes there is certainly the potential, doesn't mean it will certainly happen in reality.
Anyways, talking about that 500 number is meaningless for now, first we should replace current aircrafts, most of them, if there was the need for buying more, we'll buy, if there wasn't the need, we won't buy. It's not like Iran has already signed the contracts.
Serpentine jan, No, there is no such potential.
Iran will need some 50 big aircrafts for operating international flights, and some 100-150(at most) cheaper smaller size aircrafts for local flights, which even this one would cost a huge amount of money. Even if Iran can financially afford 50+(100-150) new aircrafts, I would have been surprised and satisfied.