If the drone, Mini ?, isn't under warranty etc. and if the main shell isn't damaged, i.e. the three? screws stay are still in the main shell and if you have a decent soldering iron I would DIY it my/yourself.
Assuming it is a mini of some sort you
1) remove the top shell.
2) Disconnect/unsolder the three wires that run from the ESC board to the motor (photograph the solder joints BEFORE you unsolder them so that you have a record of "which wire goes where").
3) Remove the two screws that secure the arm to the pivot mechanism (black bit in your photo), DO NOT lose the screws they migh be two thread specials.
4) Ease the arm off the pivot.
5) Feed the wires through the pivot and remove the arm.
6) Undo any screws still holding the pivot mechaniam to the drone.
7) Remove and replace the broken pivot mechanism then reverse the above process.
If the main shell is damaged then you are looking at a total rebuild which is not difficult but obviously more complicated.
You should find plenty of youtubes showing the process but WATCH MORE than one, in fact assuming you can find them I'd watch at least 3 some youtube repairers have appalling practises.