[lelandbatey]

To expand with more detail: there are several sites which let you enter a lit of cards and they'll generate printable PDFs which, when printed on paper, are meant to be easy to cut out. For example:

http://www.mtgpress.net/

Then, you simply slip your rectangles of printer paper into a card sleave with a real Magic card (usually some card you don't care about such as a basic land) and tada, you've got whatever cards you want and all it cost was ink and time time.