Software comps and eq would be the first choice. cost wise.
the Saffire is probably as good or better than the $350 range pre you mention. Good clean pre's, I tried that unit but it was a bit too high end$ and I couldnt get the firewire working on my old rotty pc. But it had really a great sound, imo.
If you want outboard pre's ...for ease of the analog touch...at $350
Joe Meek VC3 hasnt been mentioned yet. Its $249 new, $150ish used. Mono channel strip.
the DMP3+RNC is really a cool combo. and thats 2 channels. It would sound different than your Saffire, add some colors to your system. around $350 ish...
this combo always pops up, its been recommended long before I ever arrived here.
personally i think its the RNC that offered the cool sound...DMP is pretty plain by itself.
2cents...