Why did he say "what will we give to the man"?
Rashi citing Targum Yonasan: If he takes money, what will we give? Sha'ul did not know Shmuel's policy, and thought that he will request a wage.
What is "Teshurah"?
Rashi citing Targum Yonasan: It is a Kosher (proper) matter. This is based on the word Yosher.
Rashi citing Menachem: It is a gift upon seeing the face of a king or esteemed person. 1 This is based on the word "Ashurenu" (Bamidbar 24:17). It seems that Menachem is correct.
Malbim: This was the custom, like "v'Lo Yir'u Panai Reikam" (Shemos 24:20). The amount is based on the esteem of the giver and the recipient. This is apart from the wage for answering our query; refer to 9:7:3:2.
If they had bread, would they give bread for his wage?!
Radak: He meant, we do not have money. We do not have even bread! How will we acquire provisions for our journey? Yonason translated 'our provisions passed and are gone 1 from us.'
Radak: Ataru (in Targum Yonasan) is an expression of departed. The Targum of "veha'Bamos Lo Saru" (Melachim 1 15:14' is 'Lo Ataru.'
QUESTIONS ON RASHI
Rashi writes that they thought that Shmuel will request a wage. Why would they think so?
Radak: Perhaps he is like witches, who take money from those who ask from them.
Malbim: It is proper to pay him for his toil, to meditate in isolation [to receive an answer via Ru'ach ha'Kodesh].