You can set up accounts with passwords and privilege sets that do not allow the user to edit data in a particular table--such as your product table or that do not allow access to a particular layout--a layout where the fields in question are editable. (You can prohibit browse mode access to specific fields on a layout to keep them from being edited.)
See "Editing record access privileges" in FileMaker Help.
Thank you. I had previously set up account privileges for certain tables and that has worked well. I will try prohibiting browse mode for certain fields on tables they need to be able to modify!