Zeta advice.

Was well on my way to get the 8, 5* ships that i needed for farming zetas... Or so i thought. Since realised i need 5, 5* dark side ships to get Moff to farm them. So my question is do i buy them from the store every two days? (I finish top 200 so receive 1,200) (Roughly 40 days) Or do i grind out and get the 5, 5* dark ships i need. i currently only have FO TIE at 3* and IMP Tie/GS at 1*. How long will it take?

Cheers guys.