the difference is some brand names like Dinan make their intakes out of special materials that you could not get your hands on for the right price. I know Dinan makes theirs out of carbon fiber which has been proven to deflect heat much better. If you are also going to make a CAI it will be much more difficult than just making a ram intake. However, the downside to a ram intake is that if you do go this route you will need a heat shield, which from my experience is not the easiest thing to fabricate.
I would recommend teh Cosmos CAI, it sells for about $160 and is 3.5" in diameter. This diameter will not help because your HFM and TB is still 3" but if you ever choose to upgrade your HFM to the euro (540) 3.5" and/or wide throttle body you could definately take advantage of this.
EDIT: see this thread for more options and information