It's pretty easy to rebuild them from 2 worn seats and a good passenger seat or 2,I have done it loads and not just swapping the top halfs over so the winder is on the wrong side,I mean completely stripping the good bits from 1 and fitting to your frames.
The bit that sticks most folk is the headrests,there's a big r clip that stops them coming out,unclip the hooks between the top of the inside section of the seat and the outer and this reveals the r clips.
If you can do general maintenance to your car then rebuilding these is easy.