This ^^^ Most new spring sets are priced within about $25 from high to low, so the cheapest route will be a used set. My son had SVT springs on the car for two or three years, $50.
If you go 2" lower, pick up good struts to go with it (Konis, Bilsteins, etc...). Used springs to me would be no big deal, but I would think buyer beware on used struts at the lower ride height - Felixthecat could give you the skinny on damper life of the better sets (since he's run them).
At 1.6 drop on your car, Vogtland springs can be run with stock dampers (I have two cars over several years/25,000 miles ea - they work well), but if your car hasn't had dampers replaced, get new ones. Stock replacement dampers are inexpensive compared to the "big boys".