What!? You're staying in New Jersey and asking about shopping in New York?? Where do you think New Yorkers shop?
Kidding aside, in my old age I don't remember specific dates for sales, depending on post cards, circulars and e-mail from stores letting me know of sales. Typically they coincide with major holidays and end of seasons. For instance many of the major outdoor retailers like REI and Cabelas are having their 4th of July/Summer Clearance sales right now. Friends willing, you can save on overseas shipping by delivering to your friend's house and then lugging the stuff home yourself.
In northern New Jersey, Campmor on Route 17 in Paramus, NJ is your best bet for your outdoor needs.
For your other shopping pleasure Garden State Plaza Mall is also in Paramus. 350 stores anchored by 5 major department stores. About 30 miles north, in Central Valley, NY is the Woodbury Commons Outlet Mall. If high end/designer shopping is your game, this place is for you. Sak's Fifth Ave, Neiman Marcus, Barney's, Calvin Klien, Donna Karan, Armani, Gucci, Movado, Burberry (oh wait you don't need that one
) and others all have outlets there. Everything at a discount.
If you decide on Philidelphia, hit the Franklin Mills Outlet Mall. The Sak's Fifth Ave Outlet and the Neiman Marcus Outlet are bigger here, but there are fewer of the other high end designers. About a half hour away is another mega mall the King of Prussia Mall In King of Prussia, PA. Over 400 stores anchored by no less than 7 major department stores.
All the above, have websites for more information.
Don't forget poor New York tho
it's still a great place to visit and for shopping. Several major department stores like Macy's, Bloomingdales and Lord and Taylor have their flagship stores here, Not to mention specialty retailers like Barneys, Bendels and Bergdorf Goodman. There's always Madison Ave, Fifth Ave and other shopping meccas.
Have fun.