Headware Memory

According to the ShadowBeat sourcebook, all commercial Optical Memory Chips are of a standard 1x2x3 cm size regardless of capacity. Hence, why should headware memory cost more essence as capacity is increased, as the unit is the same size, requires the same mods etc.

References

Internal Headware Memory

Standard Optical Memory Chips in a biologicaly compatible casing, suitable for all makes of headware gear. Available in capacities per unit of 10 to 100 Mp in increments of 10 Mp, and from 100 Mp to 1000 Mp in increments of 100 Mp. It is unusable by the naked brain - a display link, or encaphalon is required. 
        Essence Cost:   0.4 
        Cost:           100 nY per Mp
        Availability:   3/24 hrs
        Street Index:   1.0 
        Legality:       Legal

External Headware Memory

This cyberware device provides a dedicated high speed port dedicated to holding a standard Optical Memory Chip of any capacity. 
        Essence Cost:   0.2
        Cost:           1000 nY
        Availability:   4/24 hrs
        Street Index:   1.0 
        Legality:       Legal
Taken from the pages of Jens-Arthur Leirbakk