Both of the above have entered the region of slang. "go" in both cases is lacking further explanation:
This might be - here is where you are to go and there you must go.
The slang meaning is really a slack response from somebody dealing with you as a customer and would in good usage, be "Here you are, sir" (offering the requested item) or "Is this what you requested, sir?"
Here/there you are covers a few situations.
Here you are - is said when the person is offering you something. That might be something you have asked for or something the person has decided to give you. Or it might be pointing out on a map where your present location is. Or it might be when you are with other(s) and looking for something; the person finding it would say (passing it over to you) "here you are".
There you are - is said when the person might have offered an explanation to your question and you seek further guidance, for a place, an item, a justification for the first explanation. It could also be an exclamation with emphasis on the 'there', when someone, possibly frustrated, finds you where they might not have expected to find you. And, as in the above paragraph, someone serving you might say, as they pass over the item to you "There you are".
