Once you have the Pegasus Boots, go to the blacksmith's house then go up one screen. Go to the left immediately to the bottom left tree and bash into it with the boots to get 30 to 200 Rupees. Once done, go back to the blacksmith's house and go right to the next screen. You should be on the bottom left corner of Hyrule castle. Return to the blacksmith's house screen then go up to the screen where you collected the Rupees. Bash into the tree and claim the Rupees again, repeating this as many times as desired.