What chapter? I would suggest that you keep technical folks out of cost related matters to the extent possible and let them make their best technical recommendations. Consideration of costs too early tends, imho, to taint the recommendations. Costs can be considered separately in the decision making process.
To give you a personal example, I was once asked to lead a project to design a LAN for a 9 story building and a couple of smaller buildings -- considerations had to be given to conference rooms, training rooms, labs, production facilities, and offices. Working with a consultant, we put together the best possible design and then determined the cost. When we presented that to management, we were told the budget wouldn't support that amount and were given a target. Knowing the best possible configuration was helpful --when we had to trim things, we knew exactly where to look and how to trim without sacrificing the quality of the overall project.