Build vs. Buy

opportunity cost (ŏp'ər-tōō'nĭ-tē kôst) noun.

1. the cost of an alternative that must be forgone in order to pursue a certain action
2. the benefits you could have received by taking an alternative action

The choice between build and buy requires more than simple arithmetic.

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In many organizations, the choice between purchasing a software package and building your own comes down to license costs. This is a very myopic/nearsighted/shortsighted view.

Hopefully some of you are already thinking in terms of TCO. This is Total Cost of Ownership, and represents the entire cost, which is not so easy to calculate.

First, it is important to understand the difference between cost and outlay. An outlay is cash exchanged for acquisition or usage (license cost) and the concept of cost is a superset that includes outlays and other expenses (maintenance, salaries).

Next, we also have to consider opportunity cost. Consider the following two scenarios: purchasing a product that is easy to deploy and maintain; or having an in-house developer use a couple open source packages to build the desired functionality. It is clear that the second option wins the "lowest license cost" battle. In some cases, a new developer must be hired, in which case his or her salary must factor into the TCO of the second option. In other cases, when a developer is already on staff, there is the opportunity cost to consider. What else could the developer work on, instead of reinventing the wheel? What benefits could that project have yielded? If there is nothing else the developer could have done, then costs can be saved in the first scenario by reducing staff. There is also opportunity cost for the user population, because they must wait for the homegrown solution.

The last item that is a little more difficult to quantify is risk. This applies to the initial creation, where developing a project internally is more likely to fail or suffer from underestimated costs. It also applies to the risk going forward of supporting and maintaining the homegrown system without the help of a vendor.

I am not saying that buy is always better than build. It is important to accurately assess the options, considering the total costs over time.