That's really cheap. A better price than I had found before.
https://click2mail.com has been the company I've been planning to use in the future for postcards. They have a 6x9 postcard that prices about $1.08 if you send more than 4 or so. They also will print a letter, put it in an envelope, and mail it at about ~$1.25 per page, if I remember correctly. But, still, for a 4x7, lob is a great price!