Eep, this is gonna sound mean...
I personally wouldn't buy the chibis, despite the price! Here is some things to look out for:
Using a lineart tool for lineart! Although they are blocky, they are easier, but they look really bad...
Shading for perspective. It looks as if she is in a 3/4 view, there is no shading to support it...
The eye design is nice, but you need to fill in the schlera!
Lastly...the mouth is hanging off the chibi. Just move it up a little!
Good luck!
Oh, and the reference sheets look really nice
