The going rate for consumer storage is $0.20/GB or less you say? Why pay so much?
Ah, but that's in 3.5" internal SATA drives. Once you're able to fit 320GB(298GB as reported by Windows) in a coat pocket without needing an additional bulky power adapter to lug around, you'll see the instant appeal of such a device.
Make sure you get one with a carrying case - which is to say - you'll likely buy the Western Digital My Passport™ Elite™ from Costco.
Starting today there is $30 off coupon in the Costco mailer on a 2.5" external 320GB drive(298GB as reported by Windows OS) - I spent $151.12 including tax today for mine. Comes with a carrying case and an LED capacity gauge on the side that lights up to indicate remaining capacity - 320gb of portable goodness.
You can sometimes ask the Customer Service desk at the warehouse for coupons if you don't have the mailer.
Otherwise you'll pay right around $160.95 to purchase online from Costco.
The device comes formatted as FAT32, which doesn't support files larger tha 4GB(2 32−1 bytes to be more precise), so format it with NTFS - that'll work with the latest *NIX & Windows OSes.
Disclaimer: I like Costco quite a bit.