the items that will cost the most are the links, link tabs, heims and bushings, tube adapters for the heims. the springs just get from a 3/4 truck, something that will dampen impact but still droop. ive heard of some running the 63" chevys but that sounds stupid. its easy to build, done it once but used 3rd gen leafs.
These pics are from Gabes old rig, if i remeber correct. met the guy once at reiter. but this is his setup. worked awesome