IF you decide to do nitrous, you have to take alot of things into consideration... For one, your motor wasnt built to handle the heat, pressure and abuse the sudden shot of nitrous will give it... Keep in mind, when you use nitrous, you are basically forcing more pressure into your cylinder chambers... The added heat will cause things like your rings and even pistons to expand... When this happens it increase your compression... When I had my motor built, one of the things we discussed was the possibility that I may use a small, say, 50 shot of nitrous... So my motor was build for that variable... If I wanted a 150 shot, the tolerances would have been totally different... If you do nitrous, do a wet shot, and dont do more than 50-60hp...
If you want to cool your intake charge, use meth or water injection, cheaper, and water is free...
As for cost: I totally agree with Figgie... If its a cost v/s performance thing, the nitrous may appear to be a benefit in the short run, but in the long run, the turbo will do you much better...
Look at it like this...
Nitrous kit: $550
Bottle warmer: $100
Purge kit: $100
Remote turn on: $250
There's a thousand dollars, and you havent even filled your bottle... You know what kind of turbo you can get for a $1000?
Just some food for thought man...
) the old fashioned way 
