I had the same noise. It's pretty interesting, right? LOL
After a year of putting up with that "metal" sounding noise, bringing it to various mechanics and even speedshops, I brought it to my autobody place owned by my friend's father. He diagnosed the problem in about 20 seconds -- it was the outer tirerods. The reason why mine wore so quickly was because I put on a pair of aftermarket rims (18 inch chromes, pretty heavy) about two years ago, and they had been wearing down the rods quicker than normal. The tirerod's cost about $10 a piece (if even that), and the installation by his mechanic at the shop took about 30 minutes or so (only because he had move the rotors/calipers out of the way.)
I'm almost *absolutely* positive this is your problem. The only place that was (not) even close to figuring out what was wrong was Gemini's Auto (I think everywhere else it might just be called Firestone), and they were going to charge me about $1500 for a brand new steering column. Don't get duped!
I hope this helps you!
~ Brat