Would it be possible to get a Garmin mount built into it
Anything is possible, Hippy wanted accommodation for a QuadLock, any savings from bulk buying would be contingent on you both wanting the same thing. My tarty Ventus bridge accommodates a a Garmin mount where there isn't room to twist the Garmin between the bars, but a simpler and much cheaper solution would work if there's space to do the twist rather than having a rotating mount.
I'm not sure about Quadlock. I think I'll put my etrex mount there - if I can get one with a non-curved base. It'll probably end up getting left until too late because I'm lazy when it comes to working on bikes.
Anything is possible, Hippy wanted accommodation for a QuadLock, any savings from bulk buying would be contingent on you both wanting the same thing. My tarty Ventus bridge accommodates a a Garmin mount where there isn't room to twist the Garmin between the bars, but a simpler and much cheaper solution would work if there's space to do the twist rather than having a rotating mount.