Congratulations on your deal! I am a non-pro, so I have no experience in selling photos. However, I have framed many of my shots for my home, office and for friends who liked them. If your artwork is hanging somewhere, you should have some say in how it will be framed, and you will probably want to sign the mat. You can negotiate that with the buyer. I wouldn't want my favorite pictures hanging in cheap frames. Custom matting and framing for a 13 x 19 picture from a reputable framer will run you more than $100 I'm sure. Check that out before pricing your work.