Only if those man-days actually incur a marginal cost. If it's just employees you already have spending their time on things, then it's not worth factoring in because it's a cost you pay regardless.
It's precisely why we moved from a self-hosted demo environment server to heroku - the developers that had both the skills to manage a server and enough seniority to have access accross all the different projects could bring in more by building.
This part can be outsourced to a PaaS company, so that the company engineers can be focused on what is the company actually making money from.