I like RRE (Road Race Engineering). They're in California, and are pretty much considered to be THE place when it comes to tuning Mitsubishi Eclipses. Since the Galant (in later years) uses many of the same parts, they may carry your springs as well. They are online at www.roadraceengineering.com (they are about road racing - as in the track, not fast & furious on the street...)

www.tirerack.com also is trustworthy and typically decent on priceing. You should be paying "about" $250 shipped from most anywhere.