I suspect one person/company makes the window thingies for both Dali and SoS and for such a specialized part for such a small market I doubt anyone else on the globe would bother making the part.
Having installed the thingies and Hugo's kit, in my experience the cost of the parts is a very minor part of the job.
Removing the door handles, door panels, plastic sheet, regulators, cleaning, replacing the parts, lubing and reinstalling everything is not a small project
and even if the parts were free I'd imagine a dealer would charge $500-600 for the job.
Buy the thingies from Dali or S0S, they're a bargain at the price.
Jim