I was in the same bind about 4 years ago, needing only a few small carpet pieces; also dark blue. I contacted many places that sell carpet sets. The only place that would sell me individual pieces at the time was German Auto Tops in North Hollywood, CA. I think they've since been bought out, so their policies may have changed. Here's the contact info I have on the receipt:
Armen Oganesyan
818-766-9511
topsonebay@yahoo.com
Following up on Dirk's comment, indeed, the match was not perfect. But it was close enough to be acceptable to me; not noticeable at a glance. Apart from the cost, I did not want to go to the trouble of replacing the entire carpet set.
Good luck
