I would first check the warranty on the unit - might be covered by that, and the manufacturer of the A/C unit will replace the motor for free if under warranty - though will still cost $100-150 or so probably for a HVAC technician to do the replacement labor.
If not under warranty, is still possible the actual motor manufacturer will replace it for free.
I would check closely on motor to be sure the bracket is actually welded to the motor housing - frequently it is just welded to a large ring clamp around the motor and the ring clamp and bracket can be unbolted and taken to a welding shop to get welded (hopefully wiht some reinforcing put in so it does not break like that again. And ditto on HVAC manufacturer - they may stock or voluntarily replace the bracket and clamp and replace them for you for free or cheap, then DIY or get an HVAC tech to replace it.
IF bracket broke at a motor housing weld, then motor would have to be removed, taken to an electric motor repair shop, the housing removed from the motor, bracket welded, motor put back together - probably more than cost of replacing the motor.
IF the bracket broke a few inches away from the motor, far enough away that a wet rag could be wrapped around the motor side of the break to prevent motor damage from heat, it could be welded - but would mean you finding a mechanic who does mobile welding (and will do a professional job) - likely $150 or so. OR if you can DIY the removal and replacement, take to a welding and machine shop to get welded.
Either way, a lot more hassle getting it fixed than replaced.
However, to get back in cool air as soon as possible and if you want to avoid the3 removal and fixing and replacement hassle, may be best for you to just have the motor replaced - as I said above, probably $100-150 labor, and probably about $60-130 range if the condensor fan motor, or about $100-250 parts range probably if compressor motor, $200-350 likely if combined compressor/fan motor like some are these days.
