I had some left over Thank You cards from mine and Ken's wedding last year that I purchased at Target.
My friend's favorite color and wedding color was purple so I made a card base from basic card stock purchased in the office section of Wal-Mart. I used the plain inside of the thank you card as the front of the new card and cut out the tux and dress. I added ribbon that I had on hand from Big Lots, a purple brad, some Making Memories flowers and used purple Staz-On ink so the sentiment "Just Married" wouldn't smear.
I made sure the new card was the same size as the original card so I wouldn't have to make an envelope.