i also use a pentax auto 110. i got it on ebay a few years back, and have most of the lenses for it except for the "pan focus" lens. its a great little camera!
i shoot a variety of different formats upto 5x7, and i have to say, it is a lot easier to tote around the pentax with 6 cartridges of film (read: put in shirt pocket) than it is to lug around a 5x7 and a few lenses and film
you used to be able to buy fuji hq 110 at w-mart - at least here in rhode island it is still avail. sometimes you can find rolls on ebay for 10-20¢ each.