There are two of us on this board that do vinyl work like this. Robi has equipment that is a little better suited for doing super large letters like that...Here is our Tybee boat:





For a series of super large letters about 12' tall like in your picture (mainsail only), you are looking at something around $200 to $300 before application. With application, you're probably looking at around $400. These are pretty tricky to apply smoothly to a fabric/mylar surface but they do hold up extremely well. If I were to do an entire main and jib like this one the total would be around $1000 - largely due to the number of different colors involved.