I seem to recall these doors complete with frame are less than P2K perhaps they are all made in the same factory and a door out of one frame may fit another, so for myself I would buy the complete new unit and take out the door to fit the existing frame, now if it is not an easy fit just replace the whole unit, even supposing you were able to buy a door on its own I'm quite sure it will not be much less in cost than a complete unit anyway?