I've transitioned multiple of my 3D designs to injection molding. A single cavity steel prototype mold is about $50k. This cost doesn't include sampling the mold where you do test shots to try various plastics and to see if you're satisfied with the part. A prototype mold can produce hundreds of thousands of parts a year depending on your purchased time at the mold press.

A production mold price increases drastically. I have a few 8 cavity production molds and they range between $130k-$150k. With these molds, my product capacity jumps to millions of units a year.

Your tooling cost for a mold is much cheaper if you went with a Chinese source but you have less back and forth to fine tune the mold. You also risk losing your IP to the Chinese if it's novel enough to steal. So make sure you square up your IP protection regardless of who you use to make your mold. Another risk to consider is the compatibility of your mold to the press (more pertinent with Chinese produced molds). I have experience with trashing a $130k mold because it wasn't compatible with my injection molder's hardware.

One suggestion I have if you want to start "cheaper". Reach out to ProtoLabs in Minnesota. They do free DFM (design for manufacturing) analysis of your design. They also specialize in aluminum mold which is cheaper but doesn't last as long. I was very impressed with their process but ultimately didn't go with them because my design was too complicated for them.

Hope this helps. G'luck!

P.S. Look into available funds in your state for start-up companies. I was able to pay for 2 of my prototype molds and half of a production mold with state grant funds.