Volvo dealers in Canada, Germany and the US push the single pole units.
They charge from $1200 to $1800, plus a $281 "kit" to convert. It is a small tractor starter solenoid costing about $20 in an auto parts store

The identical Hitachi single pole starter sells for about $190 to $250. Chinese knock-offs are cheaper
The original starter that came with the engine had a Hitachi label under the Volvo green paint. The label gave the part number.

The difference between Hitachi price and Volvo is a hell of a charge for a coat of green paint, specially when the surface is not even prepared.

Only the foolish and the desperate buy "genuine Volvo parts"

I was just suckered by a Volvo dealer into $410 to overhaul my old seawater pump. I had replaced it in Scotland with an new (unpainted) Johnson pump for 135 pounds (about $200 US) The old pump needed seals and bearings, so I took it to a Volvo dealer thinking that overhauling it would give me a spare. I sure got taken for a ride.

Apart from the cost, I feel so ripped off, that I have zero faith in Volvo, and always recommend against them to people repowering. I will NEVER buy ANYTHING from Volvo, unless it is the only source of a part I need.