There was another major hoopla about this 
seller's Love Hina drawings a day or so ago, 
which I believe were determined to be only 
photocopies of the original design sketches.

As for this particular auction, I cannot tell you 
for sure, but I think that you should check out 
all his/her auctions and decide for yourself how 
the seller could obtain well over 100 of these 
sets of design sketches:

http://user.auctions.yahoo.co.jp/jp/user/Dollman9?

And also you should ask yourself how come 
virtually NO ONE is bidding on any of these 
auctions (which usually is a good indicator as to 
how authentic they are; if something looks legit, 
there should be serious bidders already).

On the other hand, someone here who knows enough 
Japanese could take a look at your auction and 
tell her for certain if the sketches are 
legitimate or not.  And also, who's to say that 
photocopies of these design sketches are not 
worth anything?

Personally, though, I remember a few American 
sellers trying to sell photocopies of Macross 
design sketches in the past for $30-40 each set, 
and they never sold well.  So I would reconsider 
spending around $100 for this Outlaw Star set (if 
they are indeed only photocopies).