I heard somewhere that it will be free for a time before people that get it later having to pay
What will the price be?
It will be free for the first to weeks.
I don't think they said what the price for the characters would be yet.
PlayStation® All-Stars Battle Royale DLC Pack digital voucher (150 available to be won; approximate retail value CDN$3 each)
... that suggests they'll be $3, but it's vague as to what would be included. (Everything seperately, 2 characters + stage, etc...)