99 Explorer Sport Reverse Band Broken

Looking for any advice on overhauling my transmission. My reverse band broke. I've had estimates from 4 shops and they all say it will cost $1600-$1900 to overhaul transmission,including replacing the torque converter. There was evidence of metal shavings when they pulled the dipstick. Car has been great and never had any other problems, has 120 k miles.
Does this sound about right to anyone else? They all say if you do an overhaul, if there are any problems, it will happen quickly rather than later...based on this would a 6 month warranty suffice?
Any advice, thoughts, etc. would be appreciated!
That pricing is in the area. Your call on the warranty. How much do they want to extend it? I find it true that real problems will show up fast. I don't know of this vehicle to be a transmission eater and some are so just do the math with the price and any deductibles. Six months should be included for no extra for the job.

Used is an option but if you like this vehicle get it done right,