Carrie's situation is not all that uncommon. Subconsciously, some women may be waiting for a man to rescue them-- that's possibly why they have no savings.
But $40K in shoes is ridiculous. Trust me -- there are ways to have great shoes and an IRA.
Last night's episode reminded me of Tama Janowitz's "A Certain Age." That book is centered around a woman who has some of Carrie's tendencies but is much more unlikable.
And I agree with the most realistic scenario being Carrie moving in with Charlotte, instead of Charlotte giving Carrie the Tiffany & Co. ring to raise caiche. Did she pawn the thing?