Does anyone know where I can get a secondhand aliminuim Swim deck with a fold down ladder to mount on my Guardian?

Have seen numerous designs that just have 2 bolts through the transom for the deck and one through the gunwale for the top handrail support.

The unit is made from aluminuim tubing and chequered plate with a ladder that swings down from the bottom pipe with 3 steps.

The wife and kids haven't got the strength to pull themselves up on just the ladder.

Preferbly a second hand unit, as I have a quote for $550-00 for a boatfitter to manufacture one....