First, you go into your local Wal Mart. Then, you go to the office supplies section. Locate the index cards. Look carefully because you want unruled or blank (same thing, I think, just differently titled) index cards. Online, Wal Mart says they have colored options for about $2.25 per 100, but I didn't see these at my local Wal Mart. I purchased unruled, white 4x6 index cards. An 100 pack was less than $1.
So, for less than $1 I had 100 potential cards. Unfortunately, I don't have quite that many friends. Therefore, these are going to last me a bit. Anyway, I made my own 4x6 invitations in Microsoft Office 2007. Then, I adjusted my printer to my index cards and printed away. I only printed on one side, so I'm not sure how they would hold up to double sided printing. However, I think they turned out fabulous! I'll be sharing them printable later on in the A to Z series.