Did Sai Baba treat his devotees differently based on their wealth or poverty when he asked for Dakshina?

No, Sai Baba showed no partiality based on a person's financial status. Chapter 14 explicitly states that whether a person was a great wealthy individual or a beggar, poor, weak, or destitute, "Sai did not know one as less or one as more." He would ask anyone for Dakshina, regardless of their background, be they Hindu, Muslim, or Parsi. In fact, he would sometimes command a great millionaire to go to a poor person's house to beg for Dakshina, demonstrating his principle of equality and his focus on teaching humility above all else.