Yes and no depending on the situation... I think re-pop dash vents go for about $50 a pair and it will cost me about $10 in material to print them. It also took a lot of time to make the 3D models and would take about 10 hours for the printer to make both parts.
It has the biggest benefit for parts that are not currently being reproduced. 3D printed parts are also not as durable as an injection molded part. Not to say that that they can't act as fully functioning parts, they still have a descent amount of strength, just not as much. I'm working on a full scale guitar body right now and pieces of it have been tapped and will hold screws. Once assembled I'm confident that it will be able to stand up to the tension from the strings without any issues.