There are a few cheaper alternatives out there - you can build your own or you can go on eBay and find something and do some mods. But, for an all in one kit and a performance boost, you probably won't find a better value than NW.

I have not gotten my CAI yet, but I am saving up to get a NW. I trust the majority of the members on here that endorse the NW products, especially for something that you can't get anywhere else (quality/ performance).