So far, only the people who think it's going to be four years explained it : it's literally the guideline suspension. Other just took a wild guess over what they think is fair and how much they like Jones or not.
Anything less than four years means there is at least one mitigating factor. The most important being obviously to find a tainted supplement, but we already know that his team tested everything and couldn't find any turinabol. Mir failed for the same stuff and he got the full guideline suspension : two years as a first time offender.
There is no magic bribe that will save Jones, the only thing that matters is if he can find a mitigating factor.