Also , how much would you estimate that this might cost me if I ever want to get it made by a good developer?
As a fellow Spartacus fan, I'd be happy to code this up for you entirely free (as a patch on-top of bustabit). I think it's a good idea, and would like to see someone do it. However, I am not in the position to host it for you, do any design changes or do anything admin related, you'd be on your own for that.
You'd also need to formalize the exact logic for the bonuses before I coded it up =)