Dubloons are used for many things in Krawk Island. For example, The Swashbuckling Academy, Smuggler's Cove and the Golden Dubloon.
Another way is to visit Coltzan's Shrine and wait till the 55th second of the neopet timing for more of a chance. You can also play Buried Treasure and find them- but it's very rare. You can also play Anchor Management in which dubloons are a common prize.
The prices of dubloons are always changing. As of March 12th, 2013, the Shop Wizard has indicated that the following dubloons are going for the following prices:
- One Dubloon Coin - 1,500 neopoints
- Two Dubloon Coin - 2,000neopoints
- Five Dubloon Coin - 5,000 neopoints
- Ten Dubloon Coin - 8,000 neopoints
- Twenty Dubloon Coin - 25,000 neopoints
- Fifty Dubloon Coin - 64,000 neopoints
As you can only combine smaller dubloon coins into bigger value one but not in the reverse, you can see that the price per dubloon for lower dubloon coins are relatively higher than those higher ones.