We estimate how much gas is required to deliver randomness to your smart contract, add 15% to it, convert it to Kenshi and then charge that amount from your VRF subscription.
VRF subscriptions can be made on the Kenshi dashboard . All payments for the VRF fees are processed off-chain and therefore are gas-free. This makes the Kenshi VRF cheaper compared to the rest.
The VRF service is free of charge on testnets.