the point is that there are multiple options available, given a bit of thought
S-3 is one, S-2 potentially another. And if you're looking for something cheap the S-2 may be the better option despite reduced capability. Note I say "may" not "is".
Just remember the USA tried to GIVE some of those S-3 airframes away, but the would-be recipients (Brazil?) jibbed at the cost of updating the avionics.