Point of order:
NICHOLS: Transparent aluminum?
SCOTT: That's the ticket, laddie.
NICHOLS: It would take years just to figure out the dynamics of this matrix.
McCOY: Yes, but you'd be rich beyond the dreams of avarice.
SCOTT: So, is it worth something to you? Or should I just punch up "clear"?
The whale tank was not made of transparent aluminum, since Nichols would've needed years to figure out how to make it based on the formula. The formula was how Scotty paid for the Plexiglas that was actually used to make the whale tank.
What? You mean Scotty and Nichols DIDN'T create the materials and machinery needed and then produce several large panels of transparent aluminum overnight?!
... That so many people get this part wrong. The explanation is right there when Nichols tells Scotty they carry in stock what Scotty needs! (This solidifying how "easy" the transaction would be.)