They say that buying car parts is a bit like buying oats. If you want premium stuff, you pay premium prices. If you don't mind stuff that has already been through the horse its a bit cheaper.
That said you can find rotors for as cheap as $20.00 to $30.00 each. Pads for about the same. Rebuilt calipers for about $30.00 to $50.00 each.
On the upper end $100.00+ for pads. $100.00 each for Brembo drilled and slotted rotors, and so on.
Also there are a lot of prices in between depending on how you intend to use them.
So tell us what you are trying to do and maybe we can be more help.