对支持CMMI目标的需求开发工具的建议

We are currently evolving our development processes in an effort to become CMMI compliant (we will start with level 2, and move up from there). We are trying to locate a tool that is inexpensive (or free) that will allow us to develop requirements in the spirit of CMMI. In other words, we need to be able to enter our requirements, track changes to them, provide alerts to individuals when requirements change, perform traceability, etc. Our projects are typically small (typically 3 - 7 developers and a tester or two).We are currently evolving our development proce