In the past, I have searched for the best price on a replacement battery. The cheapest I found was about $5k, but I did not follow up to see if the battery was actually available. I believe people who have had the battery replaced, luckily under warranty, the total cost was about $21k. Though somebody else might have differing information from personal experience.
Finding a 2014 with only 9k miles is amazing, but it sadly does not guarantee that the vehicle wont have expanded cells. If you could find a 2017 or 2018, you would get a larger battery pack, more likely a more reliable pack, and DC Fast Charging. Additionally, you would get an HV battery warranty. I would not expect the price difference between the 2014 and a 2017 to be that much, maybe $5k at the most?
The Ford Focus Electric is a great EV, but you do have to make some sacrifices, namely the lack of trunk space. I owned a Fiat 500e before my FFE, and I was very impressed with that car. I sold it because I wanted greater range and DC fast charging.