If you are persistent, you can make a nice 
collection of these if you want to.  It may be  
partly a function of being in the right place at 
the right time.

I and mine bought a number of really nice Fruits 
Basket sketches at Otakon, from a certain well-
known dealer in the Dealer's Room.  They were 
even pretty inexpensive -- none over $30.  And 
they are really, really nice;  sketches we are 
proud to have.

They are out there;  you just need to hunt them 
down, and maybe be a bit lucky.  Keep hunting!