Well, I would suggest going to Beedle's shop and purchasing the extra wallets, I think they're 100 rupees each. If you buy one then walk outside and go back in another one will be available. You can buy three and then he'll run out. They let you carry 900 extra rupees if you get all three (1 extra wallet= 300 extra rupees). Don't worry about your adventure pouch though, they don't fill it up, they just get added on to the capacity of your normal wallet unlike extra bomb bags, quivers, ect. Doing so will allow you to carry more rupees (obviously) and let you purchase more expensive items in the future.
Now, extra wallets aside, for "easy money" where your at, going into Link's room and opening his closet will reveal a blue rupee, not a ton of money, but it's still useful. Sleeping in a bed till night and going outside will make monsters appear and battling them could get you some rupees, or, better yet, treasure that you can sell at Rupin's house. If you go in Cawlin and Stritch's room at night you can sell insects to Stritch. Another way would be flying and attacking the crow-like monsters that have red rupees, some even have silver rupees. Hope this helps. :yes: