Do you have one Gadge ? I am at my mower capacity now, not planning on adding anymore unless they are very special.
No, but that's just because the larger items I seem to 'collect' aren't really suited to one.
Like motorbikes - there are four of those in my garage at the moment; three solos and a sidecar outfit.
Don't intend to be a mower collector - the three I have is about my limit. And one of those is due to be stripped for parts, when I get motivated

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I've only seen Compactus units that were about 15" shelf width, and I think you'd need 24" for mowers. However the ones I've seen were the office variety, not the warehouse ones. Even the office ones were startlingly expensive, though.
Yep, they're very pricy new, but quite often go fairly cheap secondhand, on a 'purchase and removal' basis. The shopfitters and racking systems mobs often don't seem to want to know about them.
It is indeed the wider 'warehouse' Compactus units I had in mind.