Thanks to Prentis Hale (see his review) for the tip on B&D Sheet Metal. Last winter I paid a visit to several local metal shops for pricing on a custom copper surround for my (smoky) fireplace. I took the same drawings 3 or 4 places, and was about to drop the whole project due to the 4-figure estimates I kept receiving.
Thanks to Prentis, I added to B&D to my list and was pleasantly surprised when they came back with a quote that was less than a third of the next-lowest bid I'd received. I was worried that the old adage of "you get what you pay for" would come back to bite me, but in addition to a great price, B&D delivered great work, right on time.
The only caveat I'll add is that you need to know what you want when you walk in - they're nice folks, but they don't hold your hand much in terms of design consulting or recommendations. If you can create - or hire out - design drawings for whatever you want built, it will definitely increase the chances that what they build is what you want. That said, if you have a need for custom sheet metal work of any kind, B&D is the place you want to go.