Re:
I'm looking at the same challenge, but less bikes.
I have a steel framed 6 bike rack at present, mounted to my garage wall, but losing my garage and getting a posh shed instead. I was going to put the rack in the shed but not sure due to the weight that I can. It has been great and due to it being a framed rack, you can add a plank of wood on top and create a high shelf (i haven't done this, but have slotted boxed wheels on top.).
For my shed I'm probably going to get some simple wheel mounts and bolt them to the joists to get some of my bikes out of the way. Planet x are selling some for £15 for 5. Unless I can find a better option. Not sure what I'll do with my existing rack yet. I may see if I can use it, but having the flexibility of fitting the planet x style ones may swing it as i can put them anywhere rather than having 6 bikes in a set position.