Sasaki will likely make his decision in early to mid January.
Money doesn't matter, whatever team gets him will use their entire international bonus pool on him, part of the reason for the timing is those reset on January 15th (he might agree shortly before that but wait until after the 15th to sign). The recruiting for Sasaki is going to be entirely soft stuff. How competitive your team is, how much he likes the teammates, pitching development prowess, geography, etc.
The team that signs him is also probably going to need to utilize a 6 man rotation, or at least set things up so Roki is on a 6 day schedule. So teams will just do their shopping, and if he picks you he picks you. You need 5 non-Roki starters either way.