I would say that no matter what the price point, you're going to find some gems and some lemons. There are so many variables in exactly how the components come together to make the gestalt tone and feel of the instrument, that you can have a $300 Squier that kills it and a $1900 Rickenbacker that just isn't quite there. Also, the bottom threshold of quality is higher; companies have been mass-producing electrical instruments long enough now that they can crank out a higher-quality instrument from the factory more reliably now than they could 30 or 50 years ago. The veterans I've seen on the forum have been been pretty unanimous that the cheap starter basses one can get now are miles ahead of the cheap basses of yesteryear.
However, even so, the likelihood of getting a lemon or a gem still is reflected in the price point; You have better odds of finding a great bass (and lower odds of a lemon) at the higher prices, and vice versa. Paying more does still often translate into getting more.
The other thing is the law of diminishing returns. You can't really quantify quality or tone, but if you could, I would say that you got a 10% increase every time you double the price. In other words, if you imagined a "quality rating" - let's call it Q - and rated your average $100 bass at a Q of 100, then as the price goes up you'd see this:
Price/Q
$100/100
$200/110
$400/121
$800/133
$1600/147
$3200/161
Of course, you get the best "value" (ratio of price to Q) at the lowest price points, but if you really want a bass that plays at a certain level you have to cough up for it. It then becomes a matter of at what point you're not getting enough additional quality to be worth it. For instance, your $300 VM Squier typically rates about a 115 and your $1300 MIA Fender typically rates about a 140. But because of the variation I mentioned in any given production line, you'll have some VMs that would rate a 125 and some MIAs that only rate a 120, and thus the people saying their Squier is better than their Fender.
Just a way to think about it. "Q" is purely subjective, there's no way to measure it. But I find it helpful to think about it this way.
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