I purchased a heart rate monitoring machine last month for 125$ (selling price). However, I think that the cost could have been less that the selling price. I assume that the machine could have been sold for 50$ (assumption price) instead of 125$. What is the economic cost (opportunity cost) & financial cost of the heart rate monitoring machine?

Could you also please explain how I can do cost classifications on the basis of (i)function/activity, (ii)source and (iii)input for the following cost items: Nurse, refrigerator, vaccine, vehicle, bicycle, scales, drivers, syringes, beds, premises, drugs, nurse assistant and vaccinator? (Please make a table and do the cost classification for each cost item according to the 3 given classifications - source, input and function/activity)