Assuming that you are a printer supplying shirts to that person, I'd say that you should not spend too much time on this. If the customer is selling their shirts retail, or even wholesale, printed for $4.99 they are not charging enough for them, and in my estimation, that is on them and you should not be responsible for meeting that $2.50 price so they can make their margins... Think about your margins. If you are a small or mid sized printer you will not be able to make any money trying to make that situation work out, unless of course you are printing black on a white shirt in one location, a few thousand at a time, all the time...
