The price can vary wildly depending on what you actually need to have done and whether permits and/or an inspection are required in your area. Assuming you wouldn't need a panel upgrade, are having the HPWC installed near your main panel, and want to target 40A charging (50A circuit install), then the cost could be as low as $300... However, panel upgrades, service upgrades, installing the HPWC far away from your main panel, etc. can all significantly increase installation cost--the details really matter here (seriously, this is the difference between a simple $300 breaker install/10' wire run and a $3000+ monstrosity).
The best advice I could give would be to contact local electricians to get a quote and compare it against Tesla's recommended installers in your area--generally electricians won't charge you to write up an estimate for your project, so contacting three or four will only benefit you when it comes to finding the best balance of price and competence.