And it will break down and you not pass inspection with that. You can buy a new cat online for between 125-400 depending on the car and another 150 to out it in.
As for the OP, you got taken to the cleaners. Even if rotors, pads, calipers and brake fluid had to be changed especially on 1 axle, it shouldn't have cost you more than 750. An ASE Certified tech can guarantee the work for 1 year or 12000 miles whichever comes first. Unless you drive a relatively new vehicle never take it to the dealership. But hey lesson learned.
In fact you can purchase calipers, for about 40-80 a piece, rotors for about 30-60 a piece and pads for around 40 dollars a piece, so just in parts you shouldn't spend over 400, and someone will throw those on for another 250-300 and flush the brake fluid. That's a garage that charges around 100/hr for labor