McDonald brothers racing in thomas town, melbourne saiid it is $15 a pound, i think. might have been 16. a wet kit has two jets. one for fuel and one for NOS. a dry kit just has nos. all i have done is put a t-piece in the fuel line. and a steel braided line to the solenoid.. then another steel braided line to the fogger nossle. being a drag car i don't think you need a micro switch. as you will not be pushing the button unless it is full throttle. before i turboed my car i drilled a hole in the plastic intake tube and put my fogger nossle in there, just before the throttle body. i would go a wet kit as someone on this site said they had good luck with a wet kit and 50 hp nos jet. i will have to find it but there is a site where ya type in what psi your nos and the jet size of the nos jet. then your fuel pressure and it tells you what size fuel jet ya need.
if you can get a carby plate cheap buy it, if it has the solenoids. if not, it is no use to you. braided lines are not cheap. so if you can pick up a cheap feed line and some more cheap 4 -an braided lines and a couple of cheap 3 -an line you will be right. all the fogger nossle i have, take 3 -an lines.. fiting aren't cheap. i spent $140 on fitting for my turbo, water injection and NOS. but i did buy a lot. don't buy them from a racing shop. you can get steel ones cheaper from a hydraulic shop. or they can get you aloy ones., but cost a lot..
all you need for a wet kit is. a bottle of nos, a feed line to your nos solenoid, a nos solenoid, a braided line to your fogger. a fogger nossle, and a jet for your fuel and nos. then like a said the braided lines for the fuel..
then just wire it up with a relay and button. and an arming switch like ecotecmaniac said..
then you could go for an incabin gauge for the nos and an incabin gauge for the fuel..... i think that is about it. i will add more if i think of it..
but yeah. very simple. anyone could set it up.
i ran a 50 hp jet in a dry setup and it was crap. don't bother.. will get you going a little faster but noit much..