Tesla opinions

What's the ROI on a Tesla? For a host typically chasing cheaper, older cars, would it be worth it to go with an older/higher mileage Model S? Mileage and wear & tear don't scare me. Would an S generate enough more revenue than a M3 or Y to make it worthwhile? What kind of money does a Model S pull in daily fees? I imagine $100/day or more, ya? A '14-15 Model S with under 100k miles can be had now for under $15k. Wanna do the math on the ROI and see if it's worth it purely from a purchase price cost.

What about repairs? Those of you who have them, what have real world repairs been like? I know they eat tires, but outside of that?