I don't know about 'money', but 'power' is split across more channels in an AVR. However the power is split also between two channels in the int-amp unless it is a dual monoblock design (unlikely).
Both these units usually only have a single power supply.
With the AVR, you can run all your speakers off of one power supply no problem, or use the pre-outs to setup an external amp for perhaps the two main speakers, and still run the surrounds from the AVR. This would offload some power from the AVR to the external amp.
I've been running an Onkyo 797 for some time now in our media room. It very sufficiently powers a 5.1 system in a 15 x 18' room.
