One of the most talked about and misunderstood things about Stadia is how much does Stadia cost? Stadia will be free next year and that version of Stadia is called Stadia Base. This version of Stadia lets you access the service including multiplayer and it was confirmed that free to play will be available on Stadia. With Stadia Base you only get up to 1080p and stereo sound. You can buy games to play them on Stadia base and play them whenever you want.
Stadia Pro is an upgraded version of Stadia and costs $9.99 / £8.99 a month. Instead of up to 1080p you get up to 4k. Instead of Stereo you get 5.1 surround sound. Then you get what is best described as similar to Playstation Plus benefits in “Free games” each month and discounts on buying games. The free games is not like a Netflix system and is exactly like the Playstation Plus model. You will get game(s) each month and they are only available if you have a current membership to Stadia Pro.
Pricing for individual games has not been announced as yet. Uplay + has set it is price $14.99 a month for the PC version while the pricing for the Stadia version has not been announced. Uplay + allows you to subscribe for the monthly fee and get access to Ubisofts games including their DLC.
With the pricing if you are on the fence I would try Stadia Base next year and make your mind up from after demoing the system. As it will be free and should have a some free to play games to try this could be used to make your mind up on it.