There is a big difference in prices.
Some times I need 6 mil traces, very small holes, 50 ohm transmission line, strange shaped cutout in the center of the board, non rectangle shape.
I find the resistance between two traces varies depending why makes the board, also the breakdown voltage.
Some times I don't have restrictions. Using only their 20 drill sizes is fine. Rectangle. 20 mil traces, no holes with out plate through,
The price is very dependent on when I need the board. One to two weeks out the price is much better.