The cost of professional video editing can vary widely depending on factors such as the length and complexity of the video, the experience and skill level of the editor, and the software and equipment they use. On average, you can expect to pay anywhere from a few hundred dollars for a very simple edit of a short video, to several thousand dollars or more for a complex, high-end edit of a video with a length of a few minutes. It all depends on the quality and experience of the editor, the tools being used, and the time required to edit the project into a final cut.
It's best to get quotes from multiple video editors or production companies and to make sure you have a clear understanding of what is included in the cost. Also, you should explain the purpose and use of the final video, as it may change the final price.
Keep in mind that the cost of editing will depend on the length and complexity of the project, and it is often charged on an hourly basis, so a longer video will cost more to edit than a shorter one. A good editor is generally going to charge a minimum of $50/hr. in the U.S.. A very experienced and in-demand editor will charge $150/hr. or more.