Go to Mercay Island, dock there and leave the island, once you leave the island save the game then turn the game off. Next, turn your DS back on and go to the settings (The little DS icon), after that touch the blue square and touch the top clock and that is the date settings press the ^ arrow above the month or day icon and it should go up 1 then press A to confirm, and keep pressing B till it says "would you like to turn of the power" touch yes and the power will turn off. Turn the power back on and play the game, Beedle should be pretty close to Mercay Island, go to his ship and buy whatever you want then save the game and turn it off, turn the game back on and change the date turn it off and turn it back on, Beedle should have new stuff. You can do this as many times as you want.