Cost of Printing with an Epson 4000

The three main cost categories are: (1) the machine, (2) ink and (3) paper. This data is in Canadian dollars (CAD). Multiply by about 0.8 for US dollar equivalent.
(1) The machine
Five factors determine the cost per print of the printer: (i) purchase price including taxes, (ii) retention period, (iii) rate of return, (iv) throughput and (v) estimated disposal value.
My 4000 all-in cost including the CAD 200 of ink consumed in the initial charge-up was CAD 2903. I am assuming a 24 month retention period, 6% annual rate of return (a conservative return on alternative "safe" investments) or 0.5% per month and a disposal value of CAD 700 at the end of 24 months. Using an Excel function for calculating monthly capital consumption value based on these assumptions, the monthly amortization of the machine is CAD 97.64 (cell K6 in the table below). This is a fixed cost regardless of how many prints are made. The layout of this calculation in my Excel-based costing model looks like Table 1. (Ig...