Are you able to share where you got them from? That's dirt cheap!
Yep - See below. They are Brembo's made for AC Delco
ACDelco 172-2309 Caliper Assembly
h t t p://www.amazon.com/gp/product/B000S2OR8Q/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
ACDelco 172-2308 Caliper Assembly
h t t p://www.amazon.com/gp/product/B000S2Q5O0/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
ACDelco 18K1970X Professional Durastop Rear Brake Caliper Kit
h t t p://www.amazon.com/gp/product/B004A58TOK/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
Calipers were $232.41 + $13.11 for the spring kit + postage.
You also need pads, 350mm or 355mm rotors (355 is the best option), plus new bolts from Holden.