I really like your idea of "pricing" using multiples of the prison sentence if plea bargain isn't accepted. This forces market dynamics that the prosecution much consider. I don'w know if 2x, 1.5x or 3x is the right amount, but whatever the multiple, the prosecution knows that the accused is actually weighing the benefits based on the fact that they know they are innocent or guilty instead of treating their awareness of their own guilt as irrelevant, which is something a 10x multiple does.

At 10x, knowing that you are innocent is completely irrelevant to the issue at hand and it simply becomes a choice between the lesser of two evils, because a good is not a realistic option.