If you think about what I said that's actually covered in it.When you start any software development, alone or with a team, there is one question that must come in priority, at the very beginning of the project :
what are the abilities I (or my team) own and for which ones do I need help
All other things are pure technical problems and a matter of will. If this question is not considered and answered you will finish in the long list of the hiatus/abandonned projects.
When you do a cost benefit analysis you take that into account.
Example: If you have no developers familiar with the engine then you it would take time for them to learn it. You do that with all the tools you need and what you want to produce.
If no one on the team has a skill you think you need would you out source it, hire someone else or would it be more prudent to drop what is making the requirement.