Amulek agrees to answer questions, and the first thing Zeezrom does has nothing to do with asking questions. Why does Zeezrom ask if Amulek will answer questions, and then not ask one? In a sense, he does ask a question. He asks how serious Amulek is about the message he is delivering. Had Amulek accepted the money, the questioning would be over, and the controversy effectively ended. Mormon understood the importance of this opening ploy, and prepared us for it by setting up our understanding of an onti, so that we might have a concept of what was being offered and declined.
Verse 13 above places an onti as the largest measure of silver. The measures increased in terms of two or four. What is offered is six onties, which might be analyzed as a "full set" of four and half of another. What is offered would be considered large indeed, regardless of the actual purchasing power, simply based upon the mathematical exaggeration of the number. In our modern economy, no doubt it would be similar to being offered a million dollars. Regardless of the actually purchasing power, the emotional impact of the number itself is important. It is likely that six onties had a similar emotional impact as well as a real value.