Imbued and blood costs/general mechanics
Requirements for Playing Cards. Each library card has symbols on the attribute bar (the marble stripe on the left side) for the card type (except for master cards), the clan or Discipline (if any) required to play the card and the cost (if any) of playing that card. Some cards will have other requirements (such as capacity or title) stated in the card text. Only a minion who meets the requirements given on a minion card can play it, while only a Methuselah who controls a ready minion who meets the requirements of a master card can
18.104.22.168 does not refer to the cost as a requirement.
Doesn't really matter. www.vekn.net/general-rulings
You cannot play a card whose cost cannot be paid. If, between the time a action card is played (or an action is attempted) and the time the cost of the action is paid, you no longer can pay the cost, then you pay as much as you can and the card is burned without effect (or the action has no effect). [TOM 19960514] [RTR 20010710]
The point with cards like Sunset Strip and Ravnos Carnival (and many others) is that they either change the cost or demonstrate a way to pay the cost.