When I bought my 3 it was $2200 including the harness for my car. Now the newer 3X is $1450 including harness (economies of scale!). I've been running it for 2 and a half years now and have 80,000 miles logged in my unit.

I'm using it in a 2016 Civic Touring which was their original dev car model so it's well documented and had a modification available to get necessary torque in tighter highway turns and be able to slow to and resume from stop. Other cars may work better or worse in terms of torque and ability to control speed. They have pretty extensive vehicle listings on their site and GitHub detailing the capabilities they are available depending on the car.

https://comma.ai/shop/comma-3x

I don't work for Comma or anything, just am a fan of the tech and how it has allowed the controls in my car to get better over time rather than being stuck with what they shipped in 2016. My wife's 2021 CR-V has better stock driver assist than my 2016 Civic, but my Comma's assist experience today is far better than either stock system.