As 'bugsymike' has said, there are various tricks that could be used.
Afaik, the hinge pins are held in place by a circlip (snap ring) so possibly new pins and presumably bushes might be available from some supplier?
Looking at one supplier of 124 Spider parts in the U.S., shows that the same hinge is used for the top and bottom on both left and right doors but they're $128 each...
Another option if 'bugysmike's suggestions don't work might be to swap the hinges from top to bottom and vice-versa on the door - this should work because the door wears the top hinge pin in an outwards direction and wears the bottom hinge in an inward direction.