I'm like you and am using my airbag system for ride quality and height adjustment... No hopping for me. I purchased the complete Air Ride Technologies Air Management kit (ARC1001) for $500.
http://www.ridetech.com/productinfo/rideproe.asp
They list it as a 4 wheel Econo system and includes the compressor, tank, dual needle gauge, all fittings and airline required to get you up and running. It is really simple to hook up too, The valves are built into the gauge and the wiring is nice and simple... It only requires a power feed to the compressor and a "dash light" connection at the gauge.
Pretty low end for some folks on the board but it is going to work well for what I need for my truck.