How many parts is "reasonably large numbers"? How complex is the part? What are the inspection requirements? These items really play a major role in determining costs when it comes to volume production.
With enough volume, dedicated fixtures, gauging, process parameters, tooling and other items can significantly reduce costs.
We make complex parts where small, one-off orders, say 10-40 parts might be $150-180 each. But up the volume to the 100-300k range and the price is probably going to be in the $8-12 range. Mainly because the part goes into an entirely different, very optimized process stream when the volumes reach a certain level.
It's all based on manufacturing costs.
In the 10-40 volume part, you've got 6-8 people handling each part, depending on the feature set. These machines utilize universal type fixturing that limits process parameters. On the 100k and up volume, you've got 3 people handling the parts, and those are 2 inspection people (at different parts of the process) and 1 utility person loading the automation que. Otherwise, it's all automated, it's running on dedicated fixtures without the fixture process limits of the universal fixturing.
So you've got 6-8 peoples labor in 40 parts, or you have 3 peoples labor in 300k parts....bit of a difference in manufacturing cost....
Of course, you do have the initial and usually up front significantly higher costs of the tooling on the high volume stuff, but your piece price is going to go way down.