This idea is quite odd. The boat market and the number of builders (particularly in Europe) is huge and all try to make the boats as inexpensive as they can and they are made for all purposes including offshore sailing.
There is no way to beat in price manufactures that build about 2000 boats a year and sometimes over 500/year of the same model. This scale permits not only huge discounts in the buying of the components and materials as permits the large scale use of robotics.
The idea is as crazy as someone saying that the cars in the market are expensive and that he can make one cheaper by hand.
There are already a boat that fills or can be easily adapted to fill these needs: A plain efficient boat with a huge stability, an offshore strong boat with a very simple and efficient interior. It is the Varianta 44, made by Hanse and cost less than that: 88 000€
You can only command it by internet and the warranty is given by any good shipyard (with Hanse's approval)
The boat has some success among racers but not much in what regards cruisers and that means that the ones that want a sailboat want more than a
very spartan interior, no matter how low the price is.