Build a business case. The purchase decision is predominately a function of the maturity of the business processes within your organization. If you have already have a well-defined, automated and leak-proof system for managing documents within your organization, the business benefit from ECM may only be incremental. However, SMBs tend to fall on the opposite end of the spectrum, with proposals and contracts bouncing around several times before someone wrangles them into shape, with customer service suffering due to delays in finding the right documents, and with incorrect information sometimes leading to costly mistakes.
As with other automation projects, a business case for ECM can be built on the pillars of higher throughput, faster service delivery, lower training and on-boarding costs, lower project management expense, and greater productivity for higher-value employees. In addition, with carefully defined and vetted business processes, you can provide risk and compliance managers with greater assurance of data accuracy and approvals, which in a litigious society can drive budget approval for an ECM solution.
Investments in automation and productivity never go out of style, and the capabilities of SharePoint 2010 put powerful capabilities within reach of virtually any SMB. It may not be for everyone, but it's definitely worth a look.