I'm with you, $2k won't get you too far in the aftermarket audio world.That's what I thought. Until I dug in and realized that $2k won't even get you subs with a proper install these days.
$500 for 4 channel amp:
Alpine R-A60F R-Series 4-channel car amplifier — 100 watts RMS x 4 at Crutchfield
$500 for mono sub amp:
Alpine R-A75M R-Series mono subwoofer amplifier — 750 watts RMS x 1 at 2 ohms at Crutchfield
$700 for 6 speakers:
Alpine R-S69C.2 R Series 6"x9" component speaker system at Crutchfield
Alpine R-S65.2 R-Series 6-1/2" 2-way car speakers at Crutchfield
$380 for single 12" sub:
Alpine R2-W12D4 R Series 12" subwoofer with dual 4-ohm voice coils at Crutchfield
The total for this decent quality, but somewhat basic setup of a system is already a little more than the HK system, but doesn't include any of the needed accessories like wiring, adapters, sub box, etc. Not to mention installation which will add a non-negligible cost. All in you're probably looking at $2.5-3k for this system that probably won't sound much better than the HK system.