its not easy a while ago ebuyer did some fully boxed smcs that came with some seriously protective casing they were very very good. Looks like they are gone now
Do a search on www.7dayshop.co.uk for Smartmedia and theres a couple of really nice cases for a few quid - P&P from theres on 95p (unless your not from the UK).
Try SMC's from ebay. I brought my first from there and it came free with a leather pouch that holds 6 cards. I remember most of the dealers offered something similiar.