The only product I'd recommend are the Sylvania "SilverStar" bulbs.
The cheapo "blue bulbs" use tinted glass that reduces light output and attracts unwanted attention from law enforcement. Be warned.

From what I've heard, SilverStar bulbs tend to have a shorter lifespan than conventional halogen bulbs. Looking at long-term costs, IMO it's better to save up for an upgrade to actual HID bulbs and ballasts. I think Phillips and McCullough have kits that are priced around $500.