@Patrick K. I'm not a big fan of the model, however, I love numbers. :)
Here's how I would evaluate: (all numbers are random, just for example)
Setup cost divided by the lease term. $36,000 setup, 36 month lease term = $1,000/month
Add all monthly expenses so you know what is expected outflow.
Setup cost $1k/month, + lease $3k/month, plus insurance $1,250/month, plus utilities $350/month, plus maintenance $150/month, etc, = $5,750 expected outflow/month
Then take expected income $7,500, subtract expected outflow of $5,750 = $1,750/month expected incom
Multiply $1,750 times lease months (36) to get gross expected profit ($63,000) and subtract setup cost to get net expected profit ($63k-$36k) = $27k
To get total ROI multiply monthly expected expenses by lease term, add setup cost, then divide gross expected profit by the result (($5,750*36)+$36k) = $243,000
ROI $63000/$243,000 = ~26% or ~9%/year.
All numbers made up on the spot for visual display of calculations. Again, this is not something I have any interest in, so I would definitely want to fine tune my equations before building a spreadsheet to calculate.
Off the top of my head, this is how I would evaluate arbitrage. I hope it's helpful as a thought exercise at least.