Practically all storyboards available for sale 
are photocopies, purported to be used in the 
studio.  These come in packets (usually grouped 
by episode) much like copied settei (aka 
character designs).  All storyboards mentioned 
so far are like this.  So on the surface they 
look similar to settei (a stapled packet of 
photocopies).

Settei, as I mentioned, contain actual character 
designs and usually contain much more detailed 
artwork (such as in a traditional artbook) than 
the very rough doodles you typically find on a 
storyboards packet.  Due to this fact, copied 
settei typically fetch a considerably higher 
price than copied storyboards among buyers.  
(This is assuming you are comparing material 
from the same series, as the value among 
different series also vary.)

There are instances where there are combo 
packets which contain both storyboards and 
settei for a particular episode or story arc.  
They usually garner about the same price tags as 
a settei pack.

Some copied settei packs include photocopies of 
studio genga/douga (although an honest seller 
will still list the pack as settei).  
Considering that the ability to own actual 
genga/douga from a particular series can be 
nearly impossible to nonexistant, these 
particular packs may fetch as much money as an 
actual genga/douga set would.

As practically all these materials are in fact 
photocopies, you need to be careful and consider 
what you yourself consider worth your money.

As for actual storyboards (and in some cases 
original settei drawings), they are extremely 
rare and will fetch as much money as original 
artwork.  On the flip side, some collectors 
consider even original settei material (such as 
model cels or sheets) to be less valuable than 
production artwork (such as regular cels), since 
these have not "gone under the camera" and can 
still be reproduced within the studio.

It's really all left to personal taste.