Sergio, that is a really nice piece of artwork. I really like the color schemes you presented. Especially the light blue glow around the island that fades into the brown textured paper. It's a warm touch that works great. Your hand detail work in the terrain is rather exceptional too. Very nicely done my friend.
It does stink about not getting paid, but look at it as an investment. It is certainly a great piece for your portfolio to help you obtain new mapping projects. Add your name to it to help promote yourself. And to tell you the truth you can actually do a few things with this illustration that may make you some money. You could solicit it's use to businesses on the island, the tourism industry, you could partner with a printer on the island and sell post cards, you could create an interactive map for use online, etc. Think of ways people use maps. Of how businesses use maps. Heck, I looked online in Google Images and your map blows away anything else out there on the island! So, don't shelve this map so quick.
You have a hell of a talent. Do you have any more map illustrations for us to see?