An infinite run for headphones at a good price undercuts the rest of the product line. A short run to generate hype INCREASES demand for the rest of the product line. Grado may like the headphone hobby, but it'd be absolutely stupid to drive down your margins by having a better headphone cheaper available all the time.
SMF (the software this place ran until todd switched) is good, easy to run, and free as well...
I know dreamhost is reasonably cheap, and comes with phpbb as a free option. You'd have to do more work to install smf or vbulletin there.