I used Funkeymonkey - their website is fun. But I suspect our local sign shop would have been cheaper. Anything produced for boats is 100% more expensive.
A local signwriter is all you need if you are prepared to choose a typeface etc. We have used these people several times: Hallam Signs
Put it on with soapy water and a piece of plastic they'll supply to squeeze out the water.
I agree with Noddy 2 years ago I needed to replace the name and home port on the transom and used my local sign writer. the cost was just a couple of pounds. it is all OK so far.