Live in Bangkok? How much is a taxi fare from Wat Po to Siam Paragon?

Probably somewhere between 75-100 baht depending on traffic, you also pay for stoppage time when stuck in traffic. You can also take a water taxi on the river a short walk from Wat Po to the Skytain at Central Pier that connects to the Saphan Taksin Skytrain station for about half the price and avoid the traffic.