What are some inexpensive options for replacing a single-stall garage door?
These look nice 



You could probably build a simpler version pretty cheap.

Also if the doors are large enough, and you are ambitious enough you could put a smaller "man" door in one of the doors.  That way when you go in and out you don't have to open the large doors, but you still have the large doors for getting large projects/lawn tractor in and out.