Open-side containers are difficult to ship for one structural reason: they do not exist in depot surplus, so there is no positioned unit near you to buy. Every one of them starts as a factory build, and moving a small batch of factory builds across an ocean is what makes delivery the hard part rather than the price.
Depot stock is what carriers leave behind when they reposition equipment, and carriers reposition standard dry containers. Door Units are built for specific shippers with specific loading problems, are owned by those shippers, and stay in service with them.
So the usual route for a standard 40HC, buying a one-trip unit already on the ground in your market, simply has no inventory behind it here. The depot stock page lists 40HCs for exactly this reason.
A side-door unit is still an ISO box on the outside, so it stows normally. What changes is the handling of a small quantity of shipper-owned special equipment moving on a one-off basis: it needs a booking of its own, it is not interchangeable with carrier equipment, and it does not benefit from the volume arrangements that make standard boxes cheap to move.
That is why an empty repositioning quote for a handful of open-side units usually looks unreasonable against the value of the units themselves.
The workable route is a first trip: the new units are loaded with export cargo already heading toward your region, so the ocean leg is paid by the cargo and the containers arrive as your property after one voyage. This is not a discount scheme, it is the only arrangement in which a small batch of purpose-built containers crosses an ocean at a sensible cost.
It has a consequence worth planning for. The schedule follows cargo availability on your lane rather than the production calendar alone, so the quotation states a realistic window rather than a date that would not survive contact with a booking.
Decide the door configuration first, because it drives everything after it. Two door sets open the full side of a 20ft unit; four sets do the same at 40HC length. Specifications are on the 20FT Open-Side and 40HC Open-Side pages.
Then plan the lane and the window before the deposit rather than after it. Everything difficult about these units is on the logistics side, and it is much cheaper to solve on paper.