The “build or buy” dilemma is a common one in IT. The first question you should ask yourself is whether the technology you need is readily available in the commercial sector. If existing commercial projects aren’t exactly what you need, can they be modified to fit your requirements? If the technology has already matured in the commercial marketplace, there is rarely a need to build it in-house unless you need something highly customized, or your technology team has figured out a way to create it using open source tools. Finally, if you know exactly what you want and you have a crack team on the premises, developing your own solution might be the right choice.
For more on IT investment, be sure to read Knowing When to Take the Technology Plunge.