Viva Piñata

Just collect and have 25,000 chocolate coins available for use. Best way to earn money is breed high value Piñatas to sell. Another is to plant flowers to attract Tafflys. Direct the Taffly to a torch and they will fly through the flame and catch fire. Once the Taffly lands use your Watering can and put out the fire. The Taffly will turn into a Redhott and can be sold for 2,100 coins.

It may take a bit of your time, but you could plant a couple birds of paradise and fertilize them with the fertilizer from Ivor, fertilize them four times each and tap it four times when it is finished growing. Make sure you sell the stem before it disappears. Repeat until you get your desired amount of coins. You could use a cocoadile to fertilize the plant, too. This should take about 5-10 minutes to get 25,000 coins

Simple and Fast way to do this is using Gretcham Fetchem and Taffys that are evolved.

First you need to attract one taffy to your garden using Daisys. Once the Taffy has eaten two daisys the Taffy will become a resident.

Go to the store and purchase a flaming torch, place in garden and direct the taffy into the flame.
once on fire put the lil fella out with your watering can and Ta da the taffy will evolve into pinata worth 2100 coin.
Sell him.

Once you reach level 8-9 i think, gretchem fetchum will open in the town who will go out and grab pinatas you have had live in your garden already.
Pay her 600 coins to fetch a taffy by Express.
After a minute the taffy will be available to collect and place in your garden.
Repeat the above steps and make 1500 profit.

Rinse and repeat and you should have your 25 k in around 10 mins.