Where can i get amsoil/redline tranny oil for sr20 GL-4 type

SON240sx Automotive
1

Where can i get amsoil 75/90 or redline shockproof heavy tranny oil for sr20 GL-4 type

2

redline mt-90 = pacific mall

3

JRP

4

Is $16/bottle of mt90 right price? next mod has few in stock.