I have always said that the best map for your campaign is the map that you create yourself. We have an amazing amount of tutorials as well as the people who are more than willing to share their knowledge, all of which will get you to creating that map much faster than you think. If, however, you REALLY doubt what I just said, you could look through the finished maps and once you find some you like you could always ask the artist if you could use it. FYI, you will need to have posted 5 times before you can message anyone on this site. Failing that, we do have a Mapping Request forum (down near the bottom of the main page) where you can post your request to commission someone to create the map. I strongly suggest that you read the sticky at the top of that forum if you want some proper replies though.
I wish you luck with your project, which ever way you decide to go, and Welcome to The Guild, The Mappiest Place on the Web