May I suggest you go back a step and decide what you want. If you want new (as indicated) you need to do a lot of research.
Presumably it's for living aboard? In which case you need adequate on-board systems. Heating, cooking, plumbing, electrics etc. etc.
With each systems you have numerous alternatives. Take heating as an example: gas, diesel, solid fuel, or a combination? It is a broad topic with lots of choice and huge cost variation.
Two builders could give you a quote for a similar boat with a £20k difference purely based on the quality of equipment (engine, appliances, C/H boilers etc.)