Wedding Donation Card Favors

I would like to make my donation cards myself. However I am having a very hard time trying to find the long cardstock that are like the 'menu cards'

Can anyone lead me in the right direction as to where I can buy this paper in bulk at a low cost?

thank you for any suggestions! :)

Hi Dawn, congrats!!
I bought regular sized paper for our menues, printed two on a page (next to eachother) and then cut the paper in half.