Another suggestion, buy the receiver, L/C/R speakers and a sub. Later add the surrounds. With a decent set of front speakers, one really can get excellent sound to tide one over until being able to add the surrounds.
As an example, using a $4,500.00 budget.
Marantz, SR5007 $750.00 delivered from Vann's. 100w, all channels driven.
Klipsch b-stock RF-7 II and RC-64 II, $2,491.00 delivered from Acoustic Sound Design.
Hsu, VTF-3 MK4 Subwoofer, $900.00, delivered from Hsu Research.
Later, as you choose, surrounds, a second sub and lastly, a separate amplifier can be added to complete your need for quality, room filling sound.