Let's say for this discussion that you handle the accounting for a bakery that currently bakes mostly cookies and pies right now. Your boss has come to you with ideas for expansion of business. She would like to add ice cream cakes to the menu. She is considering whether to buy the ice cream cakes from a local dairy and just keep them in a display case in the store or if they should make the cakes from scratch on the premises. Now the text has descriptions about what costs would be relevant and which would not be relevant for this decision. However, your post should be more concerned about a description as to where you might look, ask, research to get the relevant costs to make this decision. Lets pretend that we know there is a demand for the product and so that is not an issue that needs to be researched. 

Describe how you would get the information rather than giving amounts.