@ViperDoc is on track. Here’s a Stewmac Dan Erlewine video on raising the nut slot with baking soda and super glue and a newer with a specific powder you can buy. It really seems like this is becoming more complicated than it needs to be. Unless you live in Antarctica $1600 seems really excessive. The concern about damage in shipping is legit. Starting over with a new nut is not a big deal. Nuts are made to be removed. The Stewmac site has years of repair videos. Look through them and learn all sorts of cool stuff. I almost get the feeling one or more of the repair guys is making this seem like it’s a bigger deal than what it should be in order to get you to buy a new/another guitar. It should be very obvious if this is being caused by something other than a nut issue. Some photos of the nut and first couple frets from different angles would be helpful. There‘s no need to put up with a guitar that is not satisfying to play.
Also IMO, I would forget about SS frets, refinish, tuners. The S2‘s are worth doing that to them. Save up for a better guitar.
Original with Baking Soda:
Newer with special dust: