Price of ice

This is a very mundane question, but…
My boss (a restaurant owner) is on a constant quest to rip off his customers, while we (the staff) try to foil him by any means possible. So I need to know what costs more per volume, fountain soft drinks or the ice that chills them? Additionally, we’re located in very high-cost energy (regarding ice making) San Diego.

Generally, the ice is cheaper than the soda, even in areas with high energy costs. I, personally, don’t like more than 1/4 ice in my glass, but others in my area (Fort Worth, Texas) like as much as 2/3 ice filling their cups. However, I’m a thirsty diabetic. Various people have differing preferences.