Is it “You said it, not me” or “You said it, not I”

Is it

“You said it, not me.”

or

“You said it, not I.”

Common usage dictates that it should be “not me,” yet I cannot see the reason. If one were to turn it into a question, surely it would be:

Who said it?

The answer to which would be:

I said it. (Instead of: Me said it.)

Solution 1:

A Google Books search for "you said it, not me" yields 36 unique confirmable matches (punctuated in various ways)—all in books published between 1993 and 2015. (By "confirmable matches," I mean matches that show the actual language in the match window of the search results.)

A similar search for "you said it, not I" yields six unique confirmable matches, including one in a translation of Sophocles' Electra and another in an updating of Shakespeare's Romeo and Juliet, all in books published between 2000 and 2013.

These results suggest several things.

First, writers have used both forms of the expression, but "you said it, not me" is considerably more common than "you said it, not I" in the Google Books search results.

Second, if the expression has become a set phrase, it has done so fairly recently, since the earliest instance of either form of the expression in the Google Books search matches is from 1993.

Third, the tendency to use "you said it, not me" is especially common in popular fiction. The oldest instance of the expression appears in Jackie Collins, American Star (1993), and the vast majority of the other 35 books in the set of matches are likewise mass-market novels—A Good Man Is Hard to Find (2011—not the one by Flannery O'Connor), Her Outback Commander (2011), The Dragon and the Rose (2014), Rogue with a Brogue (2014), etc. In contrast, only two of the six instances of "you said it, not I" are from murder mystery/torrid romance novels—The Twelve Days of Seduction (2012) and Saved by the Viking Warrior (2014).

If you want to say, "you said it, not me," you'll have lots of company among speakers of colloquial English. If you want to say, "you said it, not I," you can reflect that Anne Carson and Michael Shaw chose the same wording in their translation of Electra (2001) when faced with the question of which version (if either) to put into Electra's mouth during a heated exchange with Clytemnestra.