as Bernard said, I'm not sure if we need to get a forum within the CRM. Maybe an open source forum can be used in parallel of the CRM. Depends on your needs, which I don't know yet.
As for a CRM, I don't know if you looked into ZenDesk ? I know couple of small business that use it. I can get feedback, if needed. Aslo, it doesn't cost a lot per month.
My 2 cents