Primary requirements are committed by analysts in a list of issues or user stories. You can provide the customer with access to the project, thus he will be able to register requirements independently. This will not affect the cost since such users are free of charge. If it's necessary to isolate part of the project information from the customer, simply set up a special role for him and grant it access permissions that allow to register requirements, but prohibit to view or edit other sensitive project data.
If there are many customer representatives, and they are not familiar with modern trackers and ALM systems, you can offer them to use the functionality of tech support portal. This dedicated site has simplified interface. You can place useful information on it, as well as register requirements, communicate on them with analysts, monitor their state and degree of readiness.
You can also collect requirements sent via email. Tell users the email address to send their queries. Received messages will be converted into queries and placed into the issue list automatically.
Use import of primary requirements (issues) list from Word, OpenDocument, and Excel documents. You can import business requirements and system requirements as documents from DOCX, ODT and other file formats used by text editors.
When importing from Excel, you can form a requirement hierarchy. To do this, add a column with title "Heading number" (title is entered in the first row). Specify section number for each requirement from the import list, e.g., 1, 1.1, 1.1.2, and so on.
You can store all unstructured requirement information, such as messages, files, document scans, worksheets, etc., on the pages of project's knowledge base. Data can be imported (transformed into Devprom ALM internal format), or attached as files to the knowledge base sections.