Copying editing costs vary based on a variety of factors such as the complexity of the material, the format of the document, and the turnaround time. Generally speaking, for basic copyediting of 1000 words, you can expect to pay anywhere from $50 to $125 for the service.
If you're looking for a more thorough copyedit, the cost could be higher. For instance, if you're copyediting a complex research paper you may pay upwards of $100 to $200 or more, depending on the complexity of the material.
Aside from the cost, it's important to find an experienced and qualified copyeditor who is familiar with the regulations of your target publication and the requirements of the referencing style you're using. This will ensure your material is well proofread and edited in accordance with the standards set forth.
Bottom line: it's important to do your research and request quotes from a few copyeditors before making your final decision.
Here is a link to a helpful article on How to Select the Right Copyeditor for Your Project:
https://www.thebookdesigner.com/2012/08/how-to-select-the-right-copyeditor-for-your-project/