My parents just took old couches in off the street, for the cost of dragging it down the street and up the stairs.
But when you're poor, you're more self-conscious about these things. What happens when your six-year-old son/daughter brings over their friends to play? Will they get made fun of for the old couch? What if there are hair lice in it? What if the kid gets hurt from it collapsing, and you have to take them to the doctor (which will cost hundreds out of pocket)? There are all sorts of irrational fears praying on the people in this situation.