Como dizer "esse mesmo / eu vou querer esse mesmo" em inglês

Sugestão:

Não, eu quero esse mesmo
No, I'll take exactly that one

This very same/this very one

Cheers !

"No, not this one. Yeah, that's exactly the one I want!" (Isso se a gente mencionar/apontar com o dedo o que queremos)

Estaria correto se eu dissesse só "This same one"?

Also "No thanks, it´s that one that I want!" (in similar situation as Marcio has explained.)

Strawberry, it doesn´t sounds natural to me, I wouldn´t use that wording.
But then, it´s me here. Let´s wait for further comments.

PP, where did Strawberry's post go? Did s/he delete it?

Yes, somehow it has gone south, my friend!

Que tal então "I want this one though", também teria o mesmo sentido?

In certain contexts yes, in others no. I have seen it without commas, but I preffer it with: "I want this one, though."

Have used it with a comma for some time. But stopped after checking English.stackexchange.com over the (non-)use of it. It seems to me that the majority of the stackexchange's panel do not favor the use of the comma. And neither, perhaps, do the vast majority of English punctuation haters.

Check it out for yourself: english.stackexchange

One can go both ways indeed. As an answerer said, take your pick.
Anyway, not to say that I am sitting on the fence here, my reasoning is that by voicing the sentence I think that I can make a small pause. But I could say it all in just one go, then could be without commas. See?