No repops yet as far as i know. A.M.D. would be the people to get ahold of as to if they are going to be reproduced and when. Expect to pay around $500 each for them if/when they do.
There are fiberglass ones out there, but i doubt if you want them. They are primarily for race cars and the fit and finish usually isn't that good.
It shouldn't be that hard to find good used ones though. 2 door Swingers, Demons, and 4 doors are the same, the only difference is trim and emblem holes in some cases. '70 and '71 darts are the same too except the marker light is different.
Good luck.