I think a full nitrous setup from nos usually costs around $500 or something, so yeah, thats a pretty good deal, but definitely try and talk him down.

As far as if you SHOULD do it. Thats up to you. Just remember that using nitrous can significantly shorten the life of your engine. The more you use it, the more damage it will do. But as far as bang/buck, it cant be beat.

I'd say nitrous your dx engine, and when it gets damaged and old, replace it with a real engine (you know what i mean)