What does the line, "But I warn you, you're buying what will plow your own children under, "indicate about the relationship between the people leaving Oklahoma and the people staying behind?

The sale of the items is a demeaning process, for the farmers must accept ridiculously low prices for their now outdated possessions. Steinbeck is explicit about the meaning of the sales: he states that "you're not buying only junk, you're buying junked lives." This is yet another example of the dehumanizing effects of the Depression foreclosures. The situation is hopeless: there is no possibility for starting over, for the people who are leaving are now imbued with bitterness and loss. They must even give up those objects that have sentimental value out of simply necessity, yet another example of the loss of human characteristics.