Is it considered proper to bring an offering when visiting a Guru like Sai Baba?

Yes, according to the teachings presented in the Sai Satcharitra, it is a recommended practice. Chapter 35 explicitly states, 'It is not good to go empty-handed to the door of God, a priest, or a Guru.' This principle is demonstrated by the actions of Kaka, who, on his way to Shirdi with Boss Dharamsee, made a point to purchase two seers of grapes to offer to Baba. This very offering of grapes, though they were the seeded variety, became the medium through which Baba performed a wonderful leela for the skeptical Dharamsee, ultimately transforming his heart. This shows that an offering, given with respect, can be the catalyst for a profound spiritual lesson.