I bought my Model S last June with 44k miles on it, and I've put about 50k on it in the last year. Hands down the best car I've ever owned. The math for charging is VERY easy for my car; it has a 100kWH battery, and a 300 mile range. We pay $.091/kWH, so to go from 0-300 miles is that x100, or $9.10. Figure out what size battery you're looking at, what the range is, and what you pay per kWH for electricity.
This is all accurate, but slightly different for me. Mine is the S (the S and X are similar), so I have the air suspension. The Y and the 3 have conventional suspension, which is firm, and a bit harsh. They are lower cost cars.
They buying experience leaves a lot to be desired. It's VERY frustrating. Expect to be left in the dark about key items.
For long drives, the autopilot is not just nice, but now (for me) irreplaceable. I have gone back to driving our van occasionnally and notice after a drive longer than one hour that I feel tired. This does NOT happen when driving on autopilot. A 10 hour drive feels like I haven't been driving. At all. Because I haven't.
I'd like to reiterate that the 240V charger is 100% necessary. I have the Tesla charger in the garage. Mine is the 3rd (I think?) gen, which connects to a 60A breaker. Whatever breaker you connect to will be continuous use, so you'll see 80% of it's value (in my case, 48A). 240V x 48A is 11.52kW, so it would take 8.68 hours to charge to 100%. Some previous versions could connect to 100A breakers (80A at continuous duty), 240x80 is 19.2kW, or 5.2 hours to fully charge from empty to 100%. If your electrical panel can support that much current, find an older charger. I wish we would have.
Any additional questions, feel free to ask.