Thanks for that youtube recommendation, I had not seen him before. The guy I had seen doing this on youtube is mtmwood.
https://youtube.com/c/mtmwood.

Did you catch where he states that such a chopping board takes him 3weeks if he isn't working on anything else! So £750 is pretty cheap. You are right that the right timber is important and not cheap.....untill you start charging for your time, which then quickly swamps the material costs!