Depends your product complex design or not. What size.
What type of material you want to use? PP, HDPE, Acrylic?

If injection mold very pricey but finishing is the best and no limit to what type of plastic. Small volume usually use soft-mold.
Last time (5 years ago) a TV bezel soft mold with smooth finish cost about RM 100k and can last about 50,000 cycles before degradation.

CNC machine will machine out the part from 1 block of hard plastic, usually ABS.
Cost will be based on how many hours to machine out the parts.

Silicone vacuum casting is the fastest but the mold degrade after about 10 uses and only limited to using Polyurethane.
Normally reserved for people doing prototypes or sample units before mass production.
Lowest in cost.

Then there's various 3D printing devices like SLA machines and filament based 3D printers.
But these things no strength. Cost also follow hours needed.

Now you can pick your poison.