I've noticed my headlights have become dim in the last month. I've got 93k miles and never replaced them.

I called up the dealer and they said they would have to inspect it before determining it needed replacement or what work it needed (and I assume if it needs replacement it would cost 300-400 per bulb installed)

I called up another mechanic and they said they normally just resurface the hids and they should be good to go.

I had an oil change yesterday and mentioned it to the guy who does my oil changes and he said they were fine and to not replace them until they started failing.

So what do I do? Do HIDs normally dim over time? Should I replace them? What is resurfacing? Does it actually work? Which of the 3 (dealer or 2 mechanics) should I bring the car to?

 

With 93k miles on original bulbs I'd definitely say it's time to replace them. Bulbs usually color shift within 100 hours or so and will keep doing so till the eventually burn up.

Here's one of the best bulbs to run with your projectors.
http://www.theretrofitsource.com/product_info.php?products_id=148

As far as resurfacing I'm assuming they'll just resurface the plastic lens on your headlights cause I'm assuming they think they're hazed up from the UV rays.

 

My driver side bulb turned purple a few weeks ago. I called the dealer and they said that the bulb would cost $240 and since I have an '04, the bumper needs to be removed to change the bulb and that costs $215.

So I bought a pair of Kaixen bulbs from Excelerate Performance, who's a sponsor here for like $100, 6000k with blue. Great bulbs, very bright and can't complain. Then I drove over to HeelToeAutomotive, another sponsor here, to change out the bulb for way less than $214.

That's the route I'd go instead of going to the dealer. Obviously you're in MA and not SoCal so you'll have to find your own guy to rip off the bumpber if you have an '04. I have 94k miles on my car.

 

What ever you do, make sure to replace both bulbs at the same time as replacing one would just give you an odd looking set of headlights with one bulb having more light than the other.

If you are looking for better lighting at night then I also suggest changing the oem projector glass lenses with ZKW-R clear ones.

Seeing that you are in Boston, PM me if you need any help.