Why don't you guys just use a Beaglebone Black ($50), M2M cape (http://www.yantrr.com/products/m2m-cape-for-beaglebone), and a thermal printer (https://www.sparkfun.com/products/10438). BOM for that, plus project enclosure, is like $200. That's also just after a bit of quick googling...there's bound to be a much cheaper solution.
What's your price point for hardware?