Even at $25 a month, per game that's maybe about $1-2 per game per month. April has 28 games, for example, and not all of them will be on YES but even still on a per game basis, it's a pretty good deal. And month to month would be cheaper than the annual plan if all you want it for is the season. I'm guessing that you can watch games later on it if you missed one live.That seems high. I'm not in the viewing area so I'm not eligible. However I can get a single team MLB.TV package for $130.
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I'm not a Yankees fan but if I was, I'd probably sign up for it because it's not a bad value.