I have not heard negative stories about Norbert.
only one catch : he is a bit sloppy with e-mail. Do not expect prompt reply,
be prepared to not get a reply at all.
As far as I know Norbert is just a hobbyist, not a full fledged vendor.
he seems rather more interested in building than selling.
So, in case of questions and problems : call him at the times he indicates
(monday and tuesday, he lives in timezone GMT+1)
Phone nr and snail-mail address is on his website.
maybe a good idea to call and ask if he has whatever you want in stock.
if the item is out of stock, it might take a while.