Not backed up space is currently priced at $125/GB/3 years (the life of the media) so the cost, for example, of a 6GB partition, not backed up, would be
$125 * 6 = $750Backed up space is priced at $225/GB/3 years so the same 6GB partition, backed up, would be
$225 * 6 = $1350
Size Not backed up Backed up 3GB $375 $675 6GB $750 $1350 9GB $1125 $2025 12GB $1500 $2700 15GB $1875 $3375 18GB $2250 $4050