I have now owned a 1.5 in Houston for a little over 3 years, and love it.
You can manage the cost of tires, if you want to. How you drive the car obviously makes a difference. Plus, if you do not need to push the limits of tires you, you may find you are satisfied with less expensive tires that much longer than those originally on the Roadster. There is quite a bit of discussion on tire threads. I chose Continental DSWs.
I hardly notice the electricity on my electric bill.
As you probably know, the annual service costs a little over $600. There is the question of what, if any, Ranger fees will apply to you.
Tesla has worked on the electronics of my car twice under warranty.
If Austin has smog inspections, you will save that trouble and expense. (You still have the safety inspection at a cost of about $14, but that is better than $40.)
In reality, deterioration of the battery pack and depreciation of the car's value are the two big potential cost factors. Fortunately, my battery pack customarily gets 190 or so ideal miles on a standard charge (charged at 240 volts at 32 amps).
Opinions may vary on the depreciation issue from here on, but my guess is that we have seen most of the steeper part of the depreciation curve. Many people people bought Roadsters primarily because they wanted an electric car and were not prepared to live with a sports car. Many of those people have taken delivery of a Model S and sold their Roadsters to sports car lovers.
If your Roadster comes from a cooler part of the country, be sure that fan shrouds have been added, or have them added.