A property or item that is in need of repair and is offered for sale at a low price.
What we now think of as a 'fixer-upper' comes to us from the USA as a colloquial term for 'something that needs fixing up'. The first mention of this in print appears to be an advertisement for a house, in The Los Angeles Times, October 1948:
Prior to that coinage, a 'fixer-upper' was 'a person who fixes things'. That is also American in origin and an early example of it in print comes from the North Dakota newspaper The Bismarck Tribune, October 1932:
With the ink hardly dry on his accomplishment as champion batsman of the National League, it will be necessary now to add photographer, bicycler, and all around fixer upper.