Though alot of stores sell dresses that fit that description, I think the main thing Kim's dresses have in common, is the fact that most of the fabrics look rather elegant and expensive.
Key prints seen on Kim Kardashian's dresses: solid colors, stripes, animal print.
Here are some dresses for less:
ASOS PETITE Exclusive Corset Bodycon Dress
ASOS Ruched Mesh 3/4 Sleeve Bodycon Dress
$60.34 NOW $48.27
ASOS Mix and Match Lace Dress
$112.06 NOW $89.65
Oasis Colour Block Dress $103.44