I can't bring myself to spend a lot of money on Christmas cards. So usually I design a little something and get 4x6 or 5x7 prints to include with our Christmas letters. This year I am using a Photoshop template that I downloaded for free from Beauty Divine Designs' facebook page.
Also, I use inexpensive envelopes from Walmart. If you are printing 4x6 cards you can use these envelopes.