All kind of stuff...
to a novice, a Squier Affinity will look just like a Sadowsky NYC - but there is no comparison between the two.
Especially when you look at the price!
One large difference between the two is that a Squier (or other mass produced Jazz bass) will be quite variable. There is doubtless a bunch of people at the plant pulling boards off a huge pile and making bass parts out of them. They have so many basses to get out a day and they can't be fussy about how they throw them together. I'm not saying they are doing a lazy or bad job, mind you, modern assembly techniques make pretty good basses even in the worst of conditions. But you can see that the quality of any given bass is simply a matter of luck. Of how the boards and parts came to the top of the pile and got used.
A bass like a Sadowsky on the other hand costs enough that each one can be carefully inspected and the parts carefully matched. No "random" parts here. You get Roger's vision of how each bass should go together. And you PAY for that. What do you expect? If you hire an expert to do ANYTHING for you, you are going to be laying out serious coin to take advantage of their specialized knowledge! And that goes for building a bass as it does for lawyers and doctors.
Of course, the catch is that just like monkeys typing on typewriters, there is a good change that a few of those Squier basses will be excellent. It's random, but they DO exist. I've actually seen them myself. There was a thread here about how if you check enough Squier basses, you will find one where the neck just happened to be exactly quarter-sawn. So do you want to search the world looking for that "special" squier? Or pay Roger to guarantee that the bass has been optimized? Well, do you feel lucky? How much is your time worth? That's really what it comes down to.

