how much will 4/6 drop run me?? tires or drop the truck??

[jasonroman]

recently picked up an 85 gmc sierra.
just had all brakes done...which was not expected but needed.
now i know i need some tires. looking for different size front and rear for the ralleys.....but.
im wondering how much a good drop kit will cost me????
no bags or nothing crazy. what i want is good components to lower the truck.
depending on price, i may put off the tires and get the truck down first.
any help on this would be much appreciated.