omni drive transmissions

[FourPenguins]

Well there's a few point to consider. You want a four-wheel omni drive. What kind of four wheel omni drive?
Are you referring to a true omnidirectional drive (strafing ability) or simply a tank-drive with omniwheels?
If you're looking at a tank-drive with omniwheels, I advise against it. You'll get shoved sideways very easily and a well thought-out tank drive with regular wheels can turn just as well. In short, the advantages just aren't there.
If you're looking at a true omni drive, please elaborate. Crab? Omni wheels? Mecanums?
As for the kit, only time will tell. However, you can plan based on the Andymark boxes, and if they aren't in the kit, either adapt or buy some.