I ran a 9-3 w/ the following setups:
Stock OEM springs all round (se springs)+ Bilstein Sports in the rear == weird, dippy curves when turning, obviously the fronts were not as solid as the rears. It was strange...
Stock OEM springs all round (se springs) + Bilstein Sports front AND rear. Car handled very well, but was a bit 'intense' and choppy on choppy pavement; like to skitter around when having bad patches of rough pavement, but fine on nice curves / solid road.
Viggen springs all around + Bilstein sports front and rear -- Car was *mint*. Made it a little smoother than the above setup, and car stuck to the ground very well on the above mentioned choppy road surfaces. It hugged the road *very* well on a set of 17" GF wheels + poly bushes. (and 22mm rear arb)...
I'm not sure what to tell you as far as mixing shocks, but I *loved* my Bilstein sports all around, and the fronts are far more expensive than the rears, as you may have discovered.
Either way, I suggest you either get a, aftermarket lowering springs, or b, viggen springs that lower a little, but just provide a firmer spring...