Paul Ingevaldson questions the conventional wisdom on build vs. buy:

If you have custom software, you can usually accommodate a new requirement at a reasonable cost. With an off-the-shelf package, this is often impossible. If a strategic initiative can't be accomplished because of the shortcomings of the packaged system, then the cost could be incalculable. This is the true cost of off-the-shelf. You must learn to use the software the same way most everyone else uses it.

I wonder if Dell could have developed its logistics system under this type of constraint. I wonder if FedEx and UPS could have revolutionized the shipping industry when faced with this type of scenario. I wonder if Cemex in Mexico could have become a high-tech cement producer using this approach.

If it's a strategic system, and using off the shelf software makes you like everyone else, where's the win? Sure, there are commodity areas where it makes sense to buy (or use commodity OSS) (email systems come to mind), but there are also areas where you want to differentiate yourself from the competition. A point worth considering, anyway.