"It worths it", "it worth it" or "it is worth it"?

Only the last one is correct.

"Worth" is classified as an Adjective and used as one. (Although it also acts differently from all of the Adjectives.)

In your particular example, "worth" is used as an Adjective but acts as a Preposition. That's why it's normally followed by a Noun, a Pronoun or a Gerund.

Ex.

It's worth a try.

It's worth it.

It's worth trying.

What you will find is worth it, used to describe something that has a value equivalent to what is being asked for it either in terms of money or effort. In that use, worth is an adjective.

If you're having trouble understanding this, then look at 'worth' as 'having value.' then: It's worth a try. is equivalent to (but NOT replaceable by) It has value to try OR There is value in trying

It's worth it. is equivalent to (but NOT replaceable by) It has value (roughly equivalent value).

It's worth trying. is equivalent to (but NOT replaceable by) It has value to try OR there is value in trying

"It doesn't worth it." is very common.

So as, "It worths every penny of it.", do you agree?

"It's worth it" sounds very very strange.

Why can't we simply use worth as a verb? Just keep it simple.

The question is worthy of an answer. Is it an adjective, then it should have a noun following. It is suggested it could be used as a verb. English language does evolve in that direction. Would >>The question worths a response<< work? Worths=merits? Eccentric but could pass with a [sic]. The spell-check has lighted up. Grammar-check?