Some publications may require an author to pay fees (Article Processing Charges, or APCs) for publishing an article in an Open Access model. This is not automatically a sign of a predatory publisher, but be sure you understand all aspects of it.
The Committee on Publication Ethics (COPE), along with Open Access Scholarly Publishers Association (OASPA) have established Principles of Transparency and Best Practice in Scholarly Publishing. Regarding fees, they state that:
In cases where fees charged are within reason, you may be able to use your grant funding to go towards funding some publishing costs.
Funding may be available to support many aspects of your research, from publication fees to research apprentice stipends and access to additional full-text databases. Explore the links below:
Search for grant funding from government, private, and non-profit sources. Contact the Office of Research and Sponsored Programs (262-472-5212) with questions or assistance with grant applications.