1971 Plymouth Duster Rotors and calipers

Just took off Rotors and calipers from my car autozone doesnt carry the rotors. Went to another store Dandys in staten island and I learned a little more about the rotors I was informed that the hub is a seperate part from the rotor itself. New ones cost about $50 each plus shipping then they cut off the hub shave the rotor and press in the hub with the threads onto the new rotor. I feel like I'm being taken for a ride here. Can anyone tell me if I can buy one piece instead of the cutting an old hub and pressing onto a new rotor? Doesent someone sell it one piece?
:newb::banghead: