Hi I mentioned this in another thread and thought maybe it should be by itself for people to find it easier.
this is a link to a paper manufactures web site.
The give away card stock samples
( yes free card stock )
if you only go into the site for samples you have to pay the shipping on your free card stock.

BUT
if you buy one thing ( and they do have packs in 8 x 11 and 12 x 12 sized packs) then you may have 4 Sample packs (your choice) added to your order and shipped with your order for free....

So on an average buying one or two packs i spend about 13 -15 dollars and i get the pack i pay for and 4 packs of samples. the samples are something like 12 .5 x 19 inches. so each sheet of it you can cut to 12 x 12 and then use the scrap as either a 5 x7 or a 6 x 6 card...

My favorite finish from them is Linen.

http://www.neenahpaper.com/index.asp?ft=Home

hth,