You are calculating an expected value in the sense of 'mathematical operation E' under some measure not in the sense of 'I expect the price to be...'
I don't want to pick a fight or anything, your product datanitro looks nice and it's cool you are writing articles on the topic.
Where did you learn this stuff from?
By expected value, I mean the price as you'd calculate it with a risk-neutral valuation based on some model of the underlying security.
For example, if you have a model that says an option is worth $4, and it's selling for $2, you should buy it if you're confident in your model. If you can do this repeatedly on a bunch of independent options you'll make money in the long run (assuming your model is correct and you're placing a large enough number of bets relative to the probability of making money on an individual option).
I learned this with a combination of practical experience, self-study, and coursework.