Hard drives are a pretty tough market:
- Commodity status. Fierce competition between manufacturers.
- Constantly improving. Drive capacity doubles every few years. Old products have to be cleared out, often for less than manufacturing cost.
- Lack of brand loyalty. Some people might only buy Brand X - until their hard drive breaks, then they're going to shift to Brand Y and never buy X again. Most people don't care and just buy the cheapest.
There are several manufacturers: Seagate/Maxtor, Western Digital, Hitachi (formerly IBM), Fujitsu, Samsung, Toshiba (only makes notebook drives)
Fujitsu and Samsung are kind of second tier companies for hard drives - they're in the market but mostly selling to OEMs, etc. Toshiba sells to laptop builders.
I just bought a 160 GB Samsung laptop drive which will go into an iBook G4 that I am repairing for resale. Hopefully it holds up for the customer.