This is the awkward size. Small industrial units do come up through agents, but usually on a three-to-five-year lease with a bond and a fit-out. Self-storage mostly stops at garage size and isn't set up for pallets and trucks. The 200 to 400m² business ends up in a garage, a mate's shed or a storage unit that costs more per square metre than a warehouse.
A 200m² area is roughly 14 metres by 14 metres. Block-stacked, that holds roughly 120 pallets; on pallet racking, roughly 100 with the aisles. It fits a packing bench, stock on shelves, a trailer, or a tradie's materials and tools with a van backing in. 400m² is the same again: enough for racking rows, a forklift working, and regular courier and truck deliveries.
Who takes these: e-commerce sellers moving out of the house, importers with a container's worth of stock to hold, tradies and builders storing equipment between jobs, event and hire companies, and businesses that want a floor to unpack and assemble on. Grow into 600 or 900m² in the same building when you need it.