Two sources come immediately to mind:
Mt Airy Cyclery:
http://www.bike123.com
Note: You'll need to talk with someone at Mt Airy/College Park about your tires as the 700D is not a standard item and they or may not still have some of them in stock.
Harris Cyclery:
http://www.sheldonbrown.com/harris/tires/587.html
Harris sold out of the 700D's long ago, but offers some tips regarding which other size tires "may" fit on the 700D rims.