I worked in injection molding a long time ago. Unless things have changed immensely, it's far too expensive to consider for a one-off process. You'd probably be better off to look at something like Alumilite epoxy molding to produce your own. It's an exceptional product; interesting to work with and pretty fast. It's far from cheap, but my bet is that it's way, way less expensive than a custom mold.
If you use Alumilite, you'll still wind up with a mold, but it would be reusable in case anyone with a similar vehicle falls in love with your product and wants a similar bezel. That would help reduce your cost.
I'm using plastic welding (and other finishing processes) for my bezel, but I'll seriously consider duplicating it in Alumilite if others builders show me there's a market out there.
Another option is to have someone custom-build a bezel for you. Check out the work from guys like Turbocad6 and Nexson in threads here.