I got a program call "QSL Maker", I designed my own, print them out on 110 Lb. card stock, you get two per sheet of paper, cut them out, and they're ready to be filled out and mailed.
If it's close (east of the Mississippi for me) I just stamp and send the card, if it's farther out, and especially a DX contact, I put it in an envelope and mail it that way.
A buddy of mine has a printing business, and I might talk to him about printing me up a batch of good quality two sided cards on glossy stock, they tend to hold up better in transit than the card stock with printer ink, but for now these home made cards do the trick.....
Another thing you might want to check out is
eQSL.cc - The Electronic QSL Card Centre if you go with a plain basic card the service is free, most ham's (like myself) prefer to receive QSL cards the old fashion way....in the mail, but many ham's tend to be cheap, and don't mind sending and receiving their QSL's via the internet, the only thing is, if you need the QSL to varify a contact for an award or contest, you have to download it off of eqsl, and print it out....and that consumes printer ink. You can also leave your cards in their archives, but if their system ever crashes, you might end up loosing them all.
It's all a matter choice......