I sold several moderately good two letter .vc and .la on ebay last year for ~$25 - $50 each.
The .LA registry is not doing much to promote what could be a popular extension (Los Angeles, Louisiana, perhaps Latin America). Another big problem is registrars that have websites that cannot handle two letter names at all. Dotster is OK, Godaddy and others reject attempts to buy any two letter name.
Most extensions have reserved all the two letter names. There are only 676 possible in each extension that does allow them. So they really are rare.
I am holding on to a few, the renewal fees are expensive and their future is uncertain. They are a long shot (as if all domaining isn't), I do not recommend anyone put a lot of money into them, but it is nice to look at them and wonder if someday they will be superstars.