It is going to be difficult to replace a f80 door due to the flexible ribbon cable that links it to the camera. It isn't visible how one can remove this cable, not without a repair manual or knowledge of these electronic cables.
I believe I saw not long ago a replacement door latches for the F80. You can always try the old trick of just taping the door closed. Or find a repaireer that can just repair those plastic latches!
"You could just buy another N80."
Yes, you could do that until all F80s have developed a problem or 2 and no one had bothered to repair them. It will take a few more years though for that to happen!