Well, best components that money can buy. For example, I put a dozen of the best reviewed resistors in a selector switch, and put it in place of the gain resistor. Then chose the best - it was nude Vishay, VAR series, hands down. So every resistor in the signal path is VAR, and that includes the volume control, which made the vc a bit pricey - about 1K - but it's way better than what you find in quarter million pres - IMO.
Air bearings in three dimensions from New Way - they call them thrust bushings. Couldn't buy the platter I wanted, so it was machined from a 13" cylinder of cast iron. Platter mat is 1" of charcoal; 45kg including the record weight.
I just decide on the maximum I can afford, and build to that. It's always been enough to buy the best components, even if I have to make them myself, like the caps.
I'm retired, so it's only time.