This sounds like so much fun! Even to take the train up for the day!
http://www.zerve.com/shopgotham/shapemag

Shop Gotham is NYC's #1 shopping tour provider for both the corporate and consumer markets. Shop Gotham offers unique daily shopping tours and specializes in private shopping tours of all types, including bachelorette and birthday parties and incentive groups. Corporate clients include Fortune 500 companies in addition to major tour operators and vacation wholesalers.

SoHo and NoLita Shopping Tour
Activity Description Stroll NYC's hottest neighborhoods, where celebrities get their style! Shop NYC’s most unique "downtown" boutiques, enjoy exclusive store discounts, learn neighborhood trivia and see the famed Cast Iron Historic District's architecture. Experience New York like a native. A friendly and skilled guide will navigate you to a specially selected range of shops, as well as introduce you to the history and architecture of these two charming neighborhoods. This is a wonderful walking tour for both shoppers & sightseers. Please note: Most destinations are geared toward women's apparel and accessories. Highlights on this 2 hour walking, shopping tour include:
The hidden gems of both SoHo and NoLita
Exclusive shop Discounts
A complimentary " tasting"
Cast Iron Architecture
A map of the area and a list of more of our favorite stores and their addresses for further shopping after the tour