98' deville shock alternative?

I have a 1998 Deville that has leaking shocks in the rear causing the car to bottom out frequently.   I'm suffering sticker shock after pricing new ones and I figure that I will probably need new front ones soon as well.  The car just turned 170K.  Does anyone know if there is a cheaper way to go like non-air assisted, standard shocks, that would fit this thing?   I'm willing to give up some of the nice ride if I can keep it going for a few more miles.

check this place out' maybe this can help.                                        Suncore Industries - Cadillac Suspension Conversion Kits 

what do the resistors do that come with the conversion kit?