Maybe this can be a sticky. To mods to decide...
Just to give an idea to the ones who are planning to replace an existing tuner/bridge or who would build a bass from scratch.
I measured the following items on a high quality kitchen weighing scale (max. 3 kg, with 1 g of increments). So this is not as precise as a jewelery weighing scale but would give an idea.
Bass bridges:
- Leo Quan BadAss II (4 string) 226 g (including the screws)
- Leo Quan BadAss II V (5 string) 296 g (including the screws)
- Schaller Roller Bridge (4 string) 254 g (including the screws)
- Kahler 2400 Bass Tremolo (4 string) 525 g (including the screws) + 50 g (tremolo bar)
Tuners
- Sperzel Bass locking tuner 38 g (no screw needed)
- Sperzel Bass D-thing (detuner) 54 g (everything included)
- Gotoh Res-o-lite bass tuner 40 g (including the screw)
- Hipshot HB6C ultralite Clover 1/2" 53 g (including the screw)
- Hipshot HB8C ultralite Clover 3/8" 56 g (including the screw)
- Hipshot HE6Y ultralite Y key bass x-tender (detuner) 3/8" 86 g (including the screw)
- Hipshot HE6C ultralite Clover bass x-tender (detuner) 1/2" 100 g (including the screw)
- Hipshot GB7 bass x-tender (detuner) 107 g (including the screw)
- Hipshot BT3 bass x-tender (detuner) 136 g (including the screw)
- noname Gotoh GB7 style tuner 61 g
- Fender bass tuner (used on Aerodyne Basses) 98 g
- Gibson bass tuner (used on explorer) 107 g
Here are some hardware weights (bridge, tuners) 
