first of all, this should go in the anime and manga section. there's also a naruto thread that you can search through. seriously the search button will save you.
you can surely buy from places like qqcosplay.com. it's $89 for the shirt, shorts, and things for your arms and legs. but if you have sewing skills you can make your own. might even be cheaper.
for the hair just get it cut...i'd say at or a bit past chin length. in nice choppy layers. you might need help spiking it but i suggest using got2be spiking glue. it's amazing. just spike it, twisting a little bit at the tip, and set it with your blow dryer and some hair spray. it might forever and a half though. which could really be bad if you're in a rush or are too lazy. and especially if you're wearing this for more than one day.
i'd suggest using a wig. i can point you to a very good tutorial that shows how to style a sasuke wig.
What's this for? It's a wig.
What's it for? To disguise yourself from yourself.