Free Trade: Low prices benefit claim is no longer valid

Free trade will and does keep prices low for goods from Wal-Mart. However, is there a threshold below which lower prices for these goods does nothing to benefit even the lowest wage earners? I suggest that there is a price point below which it may even harm US consumers (witness the glut of clothes and toys, so much so that even many Goodwill stores will no longer accept clothes as donations).