Apart from his forgetting that lots of homebuilts go through the BMAA, and one or two through CAA direct - Stiknruda speaks much sense. Especially, in my opinion, about workshops.
Incidentally I believe that the fastest fast-build kits on sale in the UK (things like the Rans, X'Air, Sky Ranger) are taking around 400 man (person!)-hours to complete. I've also seen it shown that "amateur-build" labour on aeroplanes takes 3-5 times as many hours to do any given job than skilled labour.
G