Cheapest cost to self-design & self-build a 45ft sailboat

are you a boatbuilder or cabinetmaker/woodworker by trade? These 800hrs sound VERY low & speak of a highly skilled, very well organised person/craftsman with a perfect building place for me. Chapeau!

 

Not by trade but "involved" in boat building since childhood and as a hobby afterwards. Aside that building a hull is straight forward work as long as you know what you are doing. I think if pressed a bit and had good set of drawings could have shaped some 20% of the work easily. But it's my own design and thus skipped that part and had to make some adjustments along the build.
This hull is wood strip epoxy heavy GF sheating which is IMHO the easiest method for DYI boatbuilder in this size (LOA 20' to 40'ish). Good table saw (actually on 3rd table saw atm) and a LOT of clamps, a barrel of epoxy & few rolls of biax are the most essential things to have.,. yeah, a big tent and dry seasoned wood planks.

 

...and golden hands!