The cellular determinants of K+ secretion in the principal cell include the intracellular K+ concentration, the luminal K+ concentration, the potential (voltage) difference across the luminal membrane, and the permeability of the luminal membrane for K+.
The average cost for a brake pad replacement, resurface rotors is between $254 to $361. Labor costs are estimated between $182 to $231 while parts are priced between $72 to $130.
a set of pads are $50, 2 rotors are $100, labor should be $150. I wouldn't pay more than $300-$350 for a rear brake job, even though I think that is too expensive. If you are gutsy enough you can save yourself $150+ and do it yourself at home with some basic tools, a jack and jack stands.