If anyone has priced custom interfaces for small labs elsewhere it is a lot. I can sympathize with them using a large amount of resources for a non highly used interface.
Labcorp and Quest on the other hand are so prevalent that doing the work correctly once for many users will be a money maker for them.
Small infrequently used interfaces will still actually lose them money, whereas they'll make up the difference from the popular interfaces. If one has a small infrequently used interface, don't complain about a fee - you're still being subsidized.