Typically, somewhere between $500 and $50,000.

It is a bit like asking "what is a new car going to cost me?"  The real question is what does your video need to do for you, and what resources (time, budget) are you able to apply toward it.

If you just want to appear on a personal social media site like Facebook, you can make your own home video at practically no cost, and probably do OK.  If you need a video to help market a product rollout worth many millions of dollars, your planning and execution have to be much more deliberate.

To justify any expenditure, you need to build a business case, that is, what is the expected ROI and how will you measure it?

How do you sort this through?  A discovery process.  You need to ask (and answer!) all the tough questions about what this proposed video needs to do.  And how.   With a  a  top down mission and purpose, you can realistically begin to look at what it will cost.