Don't buy salvage. You'll have a rough go of it. Tesla makes a great car, but they make an even better charging network. Unless this is 100% a second vehicle you just want to puts around town in, you'll be unhappy with a salvage. If you can DC fast charge at 3rd party sites, you'll be unhappy with the reliability of them and the limits. Right now the limit would be ~50kWh on Chademo or an expensive $500+ adapter for ~140kW CCS. Neither option is as quick as the 250kW V3 superchargers. You'll also likely pay more on the 3rd party chargers than Tesla superchargers, but maybe not as much extra as you would have a couple years ago. If you want to do any real traveling (even 100 miles away) you want the ability to swing by a supercharger, even for 15 minutes and add another 100 miles of range back to the car. It makes even a simple weekend trip of driving an hour and a half somewhere, staying overnight and coming home so much easier than having to find working L2s that you can park the car at overnight and charge or a 3rd party DCFC that may or may not be working.
Just don't do it. You also run without a battery warranty and if that crap out for whatever reason, you're looking at $10k to $15k if Tesla will even service the vehicle. If you get an amazing deal of like $15k for a driving Tesla that just has a salvage title, maybe, but if you're paying $25 to $30k, just save up a bit more and look in the $40k range for a used Model 3 from 2019 or something...
