If you feel like farming yourself some rupees, then there is an easy way to get 200 of them by killing just one enemy. To make sure this works, I recommend bringing Fire Arrows and the Goron Mask.
To start off: leave Clock Clock through the south entrance and roll through as many patches of grass as you can while heading towards the entrance of Milk Road. Once there, you should be able to spot a very big bird flying around there. Now transform back into Link by taking off the mask and lure the bird into attacking you, once it gets close to the ground start firing arrows at it (I recommend Z-targeting him and preparing the bow as he descends).
Once you hit the bird, it will probably fly back up, if you are lucky, you should be able to get in three good hits. Repeat this process again and after six hits, the bird should die and drop a huge, orange rupee. If you have a large enough wallet, you can enter and leave Milk Road to make the bird respawn again and again, if not you can roll back to Clock Town and put the rupees in the bank before coming back. You can repeat this process as many times as you want to fill up your bank more easily (there are some nifty rewards for doing that).
Why is this bird so important, you ask? Well, there is one catch to this trick. This bird literally steals your items when he hits you and this can be any item, if he touches you, there is a chance that he will make off with your sword. Don't worry though, resetting the 3-day cycle will give you back your mandatory items and if you still had plans for the day, then it's possible to buy your stuff back at the curiosity shop.