Has anyone used a full service Design/DFM/Manufacturing partner? Thoughts on this route?

I am curious to hear if anyone has experience working with a full-service company who helps with end-to-end stages of product development? From 3D CAD modeling, to prototyping, to Design For Manufacturing to final manufacturing - what was your experience? Was this full-service type company worth the investment?

A little background: I have a product I’m trying to bring to market where our next step is the DFM stage. We have 2 designs, starting with 1 to get prepped for the DFM stage. The quote I received from a full-service company was $13k-$17k for engineering costs & DFM. This includes mechanical design (based on a 3D CAD model I’ve already provided, they have to tweak it), company reaching out to potential manufacturers to partner with, establishing the product material, preparing design for tooling. It does not include actual manufacturing, tooling or QMS.

It also does not include a prototype deliverable. For 1 prototype, that’s another $5k-8k.

I received a quote a few months ago for the same product design & to get it created in High-Res Aluminum it was $2,700 for 1 prototype.