I think it's just regular card. Not the corrugated stuff that packing boxes are made of, but the sort you might use as a border to frame a picture. I got some from an art and craft shop over here in the UK. It's about 1/16th of an inch thick. Not sure if it's the same as what Mardon used, but it looks pretty similar.
It's not too expensive, a few £/$ for a 2ft x 3ft sheet. I guess a couple of sheets of that would do you.
I guess Wal-mart might have it over there (they seem to have everything else 
), or a hobby shop/arts and crafts shop.
Post pics if you do try it, and good luck. It'd be interesting to have a showcase of members home made, card buckets. 
Si
