Gixxer cans are everywhere. This place is lousy with 'em. You've just got to know where to look.
Like mattheritage says, do a CL search, but be sure to click the 'titles only' button, not 'search entire ad', copy and paste this into the search window;
(2001|2002|01|02) gsxr 1000
For those not familiar with bolean operators, () isolates that part of the search criteria from the rest, and | or pipes represent the word 'or'. So the search engine will find any ads with any of those things in it.
Then go down the list and see who's still got their stock muffler around, usually sitting in a box somewhere with the gasket and nuts.
It took me 3 or 4 phone calls, 45 mins, and $50 to get one with 200 miles on it.
Good luck
Hope this helps