Here is a pic of my intake I made out of 3.5" mandrel bent exhaust tubing, a couple fernco couplers, a k&n air filter, and some galvanized sheet metal that I used for my intake. Seems to work good, the heat shield is painted black along with the exhaust tubing, and around the edges I just stuck some 1/2" rubber hose to clean up the rough edges and guard from scraping up the underside of the hood.
The filter cost me about $50, the tubing was around $20, and the couplers were about $6. The heat shield was just made out of some scrap I had lying around. It was relatively inexpensive compared to the kits from K&N, etc, and works good.