Quote 19
WALTER
…Baby, don’t nothing happen for you in this world ‘less you pay somebody off! (1.1.81)
Walter believes he needs to spend money in order to gain money. And, in this case, he means to spend money on a bribe to help get his liquor license. It seems like Walter's poverty has helped to make him perfectly willing to be a little shady in his business dealings.
Quote 20
WALTER
Have we figured out yet just exactly how much medical school is going to cost? (1.1.109)
Walter resents Beneatha's wish to become a doctor because it will cost the family a significant amount of money. The Youngers' poverty seems to often make them turn on each other.
Quote 21
WALTER (Picks up the check)
Do you know what this money means to me? Do you know what this money can do for us? (Puts it back) Mama – Mama – I want so many things… (1.2.220)
Walter feels limited from opportunities because of the family's lack of money. The poverty that he's been trapped in for his entire life is starting to drive him crazy.