I am thinking of fitting out a narrowboat can anyone give me advice or site links for costing out the project?

Just curious are you in the US or UK. I thought narrowboats was something the UK uses in canals. If that is the case, using american money to determine your cost, as a boat builder myself, I would say between 5,000 to 8,000 depending on how fancy you want it. You could buy cheaper materials but I wouldn't advise it.