How many pieces of the outfits do you already own? If you were stuck at 3600, I'd say that you just need to make the last piece and you'd be done. 3100 is odd place to be stuck at.
If you "talk" to the Master Fisher at the Fishing Guild, "Can you help me with the shark outfits?", what does he say?
check your bank. prior to the currency pouch automatically storing them, they went to the inventory and were bankable. You may find your wayward 500 lurking in the far flung corners of your bank.
When the day becomes the night and the sky becomes the sea, when the clock strikes heavy and there’s no time for tea; and in our darkest hour, before my final rhyme, she will come back home to Wonderland and turn back the hands of time.