You have to go to GSO for really cheap tickets. RDU has cheap tickets too, but they aren't really close (3 hour drive). The other good bet is to watch out for E-Savers from GSO, GSP or CAE which are good little mileage runs usually, but again require the 1.5 - 2 hour drive (depending on your location in CLT and which airport you're going to).

13k is a lot, is that total you're going to have to mileage run, or not including other travel you'll likely take? Really, for that many miles, you should watch the CLT-LGW route ... I'm going on 12/7 - 12/9 if you want to do a mileage run then (already confirmed Envoy both ways ... just hoping the rumors of the A330 being replaced by the 767 are ... well, just rumors).