Adrienne Spencer teaches needlepoint and also creates custom stitch guides for designers and regular stitchers like you and me. She does beautiful work which you can see in the Gallery section of her website (including the lovely backgammon board above). Unfortunately, her website doesn't talk about charges for custom guides but I expect that depends on the size and complexity of the design.http://www.adriennespencerdesigns.com/index.html
UPDATE: Adrienne has added a page that lists all the stitch guides she has available and their prices. You have to go to her Gallery to see photographs but she has made that easy by including a link on the stitch guide list page. Click and go!