Estimated costs for a new development?

[MaMaX]

Hi @ all, my name is Naum and i am located in Germany. Since i was infected by a virus called boating i allways dreamed of my own boat. A few years ago i started a similar thread here in this forum. In that time i searched for plans of a small Catamaran to build on my own. Now it's time to get serious into this project again but with a little bit different thoughts. So what do you think it would cost to develop a new boat, i mean constructionplans, calculations and whatelse necessary to make this an successful project?

What boat i'm thinking about: multihull, 5 - 6 meter, walkaround, centreconsole, outboard 100 - 150 hp max., capable for fishing purposes.

Thanks a lot in advance for helpfull post's, pm's are also appreciated.
Have a nice weekend.
Naum