want lower the car, need suggestion~

[bennjamin]

Yes.But as others have said do it right the 1st.time and replace both

to keep it on topic - re-read the OP's query.

They ask for

i want lower my car about 1"-1.5". budget below $500.
any suggestion which spring should i go? and is it just replace the spring?

So for under $500 he can only afford king springs or similar . Not aftermarket shocks too.
Aftermarket springs will be fine with only a slight drop - 1-1.5 inches is fine for stock shocks.