It depends on the shows, of course. If you watch nothing but broadcast TV, there's no contest - you can do that for free or for $12 a month.
But cable network shows? In SD, those are $2 an episode. It's difficult to get Sci-Fi Network and BBC America (the shows with the best sci-fi) for less than $60 a month. That's $720 a year.
A TV season runs about 22 episodes these days, or $44 on iTunes or Amazon Instant (before any discounts.) So that's 16 cable-only shows I could buy outright.
And with Amazon Prime, Netflix, or Hulu Plus, that number gets skewed even more... if you are willing to wait a few months, all of the popular SyFy shows are appearing on Amazon Prime, along with Doctor Who.