What is the problem with obtaining razor blades? -1984

From the text;

’I wanted to ask you whether you’d got any razor blades,’ he said.
’Not one!’ said Winston with a sort of guilty haste. ’I’ve tried all over the place. They don’t exist any longer.’ Everyone kept asking you for razor blades. Actually he had two unused ones which he was hoarding up. There had been a famine of them for months past. At any given moment there was some necessary article which the Party shops were unable to supply. Sometimes it was buttons, sometimes it was darning wool, sometimes it was shoelaces; at present it was razor blades. You could
only get hold of them, if at all, by scrounging more or less furtively on the ’free’ market.