Super Fort :There most still be a large supply of spares for them.
The A-4 first flew in 1954 and was operational in the US in some fashion until 2004.
The Ms were the last new built A-4s, production continued until about 1988.
The A-4 remains in service with Israel, Singapore just retired most of theirs, NZ has theirs up for sale, Malaysia is still flying some, Argentina has just acquired and upgraded the Marine Ms, and Brazil is now operating the Kuwaiti aircraft as has been discussed.
Because of all this activity over the years there are spares all over the world.
It is difficult to support the B,C, L, & Q models though, due to lack of Wright J-65 engine spares