I got mine through SDtrucksprings and I ordered my compressor through xtremediesel.com which is XDP.
There are alot of places that might be cheaper but, then I searched for coupon codes, on XDP, the compressor was $10 more listing but, they had the best coupon code which made it cheaper in the end.
On top of that airlift was running their mail in rebate at the time.
Airlift is running the same special still. Buy and Airbag kit or compressor and get $50, if you buy both you get $100 back by rebate. It ends today according to Airlift's website.
However, in a few months they will likely run it again, that's what I noticed anyway.
2012 Keystone Sprinter
Still sticking around for the good people and advice.