You can sign up for a free one-month trial to try before you buy. YouTube Red is $10 per month and currently only available in the US, Australia, New Zealand, Korea and Mexico. You will not have to pay for both services separately. The inverse is true too if you already subscribe to Google Play Music, you also get access to Red automatically for free. The final benefit is that you get a free monthly Google Play Music subscription (normally $10) included with YouTube Red.