Just spent 3 weeks in lovely Roatan. Here is a lesson I learned the hard way.
The actual Taxi prices are as follows: Airport to West End or West Bay should be between 25-80 Lempires. NO more than that!! There is a sign posted in the airport(probably by one of the cabbies) that gives the price of around $20.00 dollars to West End. Do not pay this! If you can not negotiate a fair price at the airport, simply walk the 100 yards or so to the road and flag a taxi down. This may take 5-10 minutes but by doing this you will likely save $16-$18 one way. This leaves you more money for Salva Vida!!(local beer)