I believe the same cost as the respective morph. The aberrant describes the PATTERN, not the morph. They are most commonly found in normals and macks, or so I've been told. I have an aberrant little girl that I'll hopefully be proving out soon.
Basically, you could have two Macks...a banded and a aberrant. In most cases, they would be priced the same. These are just my views and what I have seen