It was created by Martin van Lith from MCWS in the Netherlands. He's a genius at this type of modification for scale models. By the way, I have no reason to promote him other than I paid him to do this work for me (in case the mods think this is an advert...)
It depends what you want. In my case, despite the donor model being widely available there was still a fair amount of customisation work involved including some 3D printing of some parts. None of this is going to be cheap... But you know what? It's worth every euro...