Well, you'd have to take the monorail or the ferry to the TTC and get a cab from there (or it might be quicker to walk to the CR and get a cab there).
A cab from the GF to the BW is about $18 including tip. So I'd say a cab from the TTC or the CR would have to be at least $25 plus tip, possibly more if there was heavy traffic. You'd save a lot of money taking a Disney bus to the All Star Sports or Pop Century and taking the cab from there, they wold both put you a good $10+ dollars closer.
Anne