If you figure in the cost of the mold on the injection molding the printed numbers will be a lot higher. The main strength of injection molding is quantity production costs, but the mold is Thousands of dollars to produce and maintain.

The change over to a different part for 3D printing is a lot easier too! You could print all the parts for an assembly, one at a time, and make four assemblies, when they are ordered, with zero inventory. :)