We got coloured stick-on letters from a car shop - look very good (£1 each as I recall) - took a while to get them to look right when curved around the horseshoe.
If your based in Hampshire, try Signtec Graphics & Signs based near Botley.
They do a lot of marine graphics (They do all of Northshore's and others) and have very competative prices.
Contact Colin on 01489 890404. web page
No connection apart from being a very satisfied customer over several years!
I've used Kandi Graphics very happily. They will use your choice of font if they don't have it, useful when you have a boat named Jedi and want a Star Wars font.