Vistaprint is running a deal where you can get 20 invitations or announcements for "free". They aren't exactly free, but they are really cheap! Vistaprint ends up charging you $2.99 for 20 invitations plus shipping. When I checked on shipping, my costs were $4.14. This may vary so check it out before you buy, but I'll bet it is still a good deal for you! In my case, 20 invitations would cost me $7.13, or about $0.36 an invitation. Not too shabby! If you want to buy more than 20, higher quantities are currently 50% off.
I love their invitation deals because you can make whatever you want out of them. Birthday party invitations, baby announcements, thank you cards, whatever you can think of! You can even use your own photos on them!