I agree with lsiberian. Blow it on the speakers first. I'd even get some outdated garage sale receiver for now, if that would let me get decent speakers to begin with. Modern receivers are generally designed to be ruler flat, as long as they aren't clipping, whereas with speakers, the greatest variations in SQ are found, as far as AV purchasing choices.
Spend first where electrical energy is converted into mechanical energy, because this is the toughest part: Speakers.