None of these available mounts looks really appealing to me. In fact the lack of a good aftermarket mount is keeping me from buying a Garmin. I don't want a fridge on my stem. But the other mounts that are mass-produced all lack in at least one area on my checklist:
1. symmetry: device should be right in the middle
2. symmetry: around the stem (no one-arm mounts)
3. clean lines: device should not protrude to great extent above the stem when looking from the side
4. should take up as little space on the bar as possible, so definitely no space allowed between stem and computer mount (as in Sram pic)
5. cheap (40€ is a blatant ripoff, are you listening K-edge?)
And I haven't even got to the point of function and weight.