Doesn't get much cheaper than RC but you get what you pay for. Keep in mind 4" is the magic number where you start getting into SYEs and other mods besides just the lift.
SYE = Slip Yoke Eliminator. Essentially you can go so high without spending alot of money. When you get over 4" or so it starts to get expensive - new driveshafts, SYE, brake lines, control arms, trackbars, etc.