I've got roughly $1,300 in my airbag setup, but some of the stuff was used and some was even free from friends. Most setups are between $1,500 and $3,000.
I just spent $2400 on mine, and I still need to get fittings, a pillar pod for my gauges and another water trap. Sooooooo I'm planning on somewhere in the neighborhood of $2700 when its all said and done.