Why not look at number of animals produced and amount it costs to raise them to a sellable size and how much it costs to feed the adults etc.
A friend of mine working in computer programming wrote a data base for me so that I could keep track of egg production/sales/hatch rates/housing costs/feeding costs.
Its a great little program.
Maybe you can work this into something???
Just a thought...
Matt and Susan
High Quality Reptiles