I think the real parable to TASTAAFL, isn't to do with value but rather is to do with knowing costs.

At it's face it appears TANSTAAFL ignores that things can have different marginal values between individuals. This difference in marginal value is why trade happens at all, and people only trade if it increases the value of their world. What this means is, even if there is a future 'cost' to something taken for free, since value is subjective the cost may be nothing of value to you. But conversely it could also be something of tremendous value to you.

That is why I think the real lesson is about knowing what you are trading, and that something "free" simply means you lack knowledge of the actual cost upfront.