Want one? The prices below are for still pixel images, but you can add another $10 to normal or boss sprites to have a simple animation like the sample here.
-Normal enemy, $20 - around 64 x 64. Simple design; you can give me an idea for what you want, or just a ref and let me make up something.
-Boss enemy, $30 - around 100 x 100. More complicated design, same stuff as above!