Converting from Chlorine to Salt

That's high BUT it should include the cost of the system, the plumbing work, the electrical work and hopefully adding salt to get the proper salinity level for it to work. Since I don't see automation in your signature this price should also include a physical timer so that the cell doesn't turn on until after the pump is running and so the cell turns off before the pump turns off. This is so the cell isn't one without water flowing.
 
I have considering converting and was quoted - $ 2355 for the conversion.
Includes TCELL940 with 3 yr Parts only warranty.
Hayward W3AQR9 AquaRite
Both of those cells are undersized for your pool.
The 940 puts out 1.47lb/day or 6 FC in your pool running 100%, 24 hours. You don't want to run 100%, 24/7.
The W3 is .75 lb per day.

Find a cell that is at least a 40K cell and produces at least 2lb/day. (Hayward only goes up to 1.47).

Here is a comparison chart with outputs.