Copies of settei have been selling on yahoo for a 
long time, some with fairly bad copier artifacts. 
But yes, copies of sketches have been poping up 
for sale, for example check mandrake's auctions.

Ex: NARUTO genga copies
Descript: copied genga 233 pages set

http://ekizo.mandarake.co.jp/auc_e/itemInfo.do?
itemId=03012777430100001

Anyrate people seem to be buying, I guess it's 
their money, not sure what the appeal is though.