In advertisements, o.n.o. is used after a price to indicate that the person who is selling something is willing to accept slightly less money than the sum they have mentioned. o.n.o. is a written abbreviation for ‘or near offer’. ( BRIT )
O.N.O.
Meaning of O.N.O. in English
Collins COBUILD Advanced Learner's English Dictionary. Английский словарь Коллинз COBUILD для изучающих язык на продвинутом уровне. 2006