There was a business at showing at an exhibition - Pulse 2008, Earl's Court - that sold letterpress cards and postcards on rough recycled card. I've done a quick google and can't find more, but they looked stylish at the time and might be worth looking out for. The Pulse 2009 exhibitors are still listed online and Cardelicious.com looks similar - they might know who does letterpress stamping on recycled scraps if they don't do it themselves.
Old-fashioned brown card luggage labels look as though they're made out of recycled paper.
Otherwise it's a question of quick and nifty ways to cut your own - I think the biggest self inking rubber stamps are 1.5" x 3", or maybe some kind of variation on a John Bull printing set could do some of the lettering? The more heavy duty ones are Adana: http://britishletterpress.co.uk/presses/small-presses/adana/