Depends on your needs atm. Are you in that stage of the game where you need meta ninjas to stay relevant? Then, maybe saving for Masked Man is a good idea.
Otherwise, you can save further for power-boosting items especially now that Lucky Board event will arrive soon.
As for Tobirama, I don't see him doing well in the current meta, as ninjas with more utility and damage at the same time could easily replace him.
He could be good for ranked battle, though. So yeah, not worth going for him.