I'm also running with the Vec 2 ($1,000 itself). I bought the wet 200hp kit from Nitrous Express (NX) and the entire kit cost $600. I fabricated my own smooth tubes and solenoid brackets and did all the plumbing and wiring myself. Other than a set of colder spark plugs, those were the only costs for me.
If you know a little about wiring and are patient, you can do it yourself. And the Vec 2 is awesome as a nitrous trigger. I believe PLUMCRAZY and I both use the Vec 2 to trigger the nitrous ONLY at wide open throttle and ONLY between certain RPM's (3300-5200). This way you don't have to use that cheasy micro switch the kit comes with.
But then again, PLUMCRAZY has a really bitchin custom-painted, dual-tank setup in the rear. I'm only using the 10 lb. tank the NX kit came with.
Oh, and one other expense you will HAVE to have is a bottle heater. A good one will cost you a couple hundred bucks. Good luck!