6.1.4 --> 7.0.6
$45/per version
as for your modules, kiss those good bye, unless you have the mod developer at the ready to provide you with the latest releases and upgrade your module, you are most likely somewhat doomed.

40K users, not a real problem, just hope your server can stand the strain of the migration script.

as for ccbill, my suggestion on that would be to get the addon module from martinboi dolphin subscriptions, and i do believe he has CCBill written into there, see more if not, you can use
Below is the legacy version of the Boonex site, maintained for Dolphin.Pro 7.x support.
The new Dolphin solution is powered by UNA Community Management System.