I was thinking about a shipping container myself, rather than a shed.
There’s room for a 20x8 foot container here:
However the cheapest I’ve seen so far in Canberra is $2k.
I thought a layout something like the following could work:
With anything that’s been expelled from the space being placed in the back of the container, backing forwards through it, and once junk reached the start of the container, anything at the back would be thrown out.
Just an idea.
(Don’t get me wrong, I love sheds, but there’d need to be strict rules about what it’s used for so it doesn’t just become a dumping ground)
I did check, the space you mentioned is perfect for that shed, and at $500 it’s damn tempting, we’d just need to organise delivery (Which I fear would almost be the cost of the shed itself).