Just get a cheap paper cutter at staples and a pack of comic backing boards. That should get you close enough.
Or search ACEO under crafts on Ebay.
http://www.ebay.com/itm/ACEO-Paper-1...item359c493aa1
I haven't bought from any of the sellers since I have a cutter and a nearby craft store.
Some modern card products came with heavy blank inserts for a few years, but I forget which. Maybe 2010 or 2011 A+G or Gypsy Queen.
Steve B