I was just at Target this morning and bought 10 packs of cards/envelopes holding 10 each; the envelopes conform to A2 size, though they are a bit wider than 4 3/4 inches. They were 49 cents per package! I also picked up two boxes of 16 cards and envelopes which are 5x7 inches; I think those were 69 cents each. Unfortunately the cards are too flimsy to use as bases, but they are non-shiny and made from recycled materials. I will recycle them once again.
(P.S. Here's a tip for those of you who forget to bring a tape measure to check the size of envelopes before purchasing: Go to the scrapbooking/papercrafting aisle at Target and grab a package of A2 envelopes in a clear cellophane wrapper so you can measure the on-sale holiday ones next to it. Some person had left one of those packages in the marked down holiday cards section so I was able to use this trick myself.)