Manufacturing cost that absolutely affect the overall feel, sound and quality of a bass: Direct labor, wood, electronics, hardware, tools .
Operating cost that does not affect the finish product but the manufacturer still needs to consider them in order to set the selling price, meaning that we paid for them: Facility (rent, taxes); Utilities ( electricity, water, telephone etc) ; marketing/selling (website, publicity, endorsements, events), etc.
Now , I am not saying that there is not difference between a high end bass - Expensive ( Sadowsky, Fodera, etc) and a low end bass - Cheap ( SX, Squier etc), of course that there are difference in quality, the manufacturing process, components and level of skills of the people that were used to build the bass are different so a difference in the quality of the finish product is expected. Do the most expensive sound better? That depends on the ears of the person listening.
Now, how much that quality worth is up to you. To me, there is a limit in quality, once you paid $1,500-$2,000 you are getting the best possible quality you can have: Top hardware and electronics, excelent wood and finish and if you are not happy with the fretboard work you can send the bass to a world class luthier for a dressing.
My last comment. Some people think that they don't need to spend too much to get the job done, some other are willing to spend a little more and get better quality and some other people likes to have the most expensive available options: Exhibition grade tops, exotic wood fret boards, custom color, be involved during the bulding process: call the builder, exchange emails, etc. Whoever you are is ok, just be sure to play the hell out of your bass.