Hi Liz,
Blogger has become a problem lately. When I respond to a comment it will attach it to a different comment. So here's a pretty typical answer to your question. see below for a link.
The actual cost for a battery replacement will be between $3,000 to $15,000 depending on if it is a rebuilt battery pack and a brand new battery pack. The warrantee looks like 10 years or 100,000 miles. Then if not re-buildable there will be a battery disposal fee to get rid of all the bad chemicals inside them and the cost of repairs will make the car nearly worthless in trade-in value. We are a long way off from electric cars being affordable transportation for everyday people like us.
Here is a link that will answer your questions:
https://www.currentautomotive.com/how-much-does-a-tesla-model-3-battery-replacement-cost/