Portable HDD as Internal HDD

[seong]

I know most of you'll say 'Mroogle' or 'Google it yourself', but I just wanted to ask any of you with experiences.
Near my house, there is a computer store which sells Internal HDDs and External Portable HDDs. I wanted to get 500GB, and got stuck with either WD Blue Scorpio or cheaper external portable HDDs.
How come the portable HDDs are cheaper than Internal HDDs? Aren't Internal HDDs supposed to be "cheaper" because it doesn't need a case?

 

[lewis82]

They sell way more external HDDs than internal HDDs (in 2.5" form factor, anyways) as most people that buy a laptop will be afraid to open it. So economies of scale appear.

Also, some drives skip on the SATA connector and feature only USB 2.0.

EDIT: to clarify my last sentence, there is no SATA connector on the drive itself, only USB. I'm not talking about the enclosure.

 

[AlphaDogg]

I got a 320GB seagate external HDD. I opened the casing and put the drive inside my white macbook. I have since upgraded to a MBP, and that very same hdd lives inside the MBP now.