[UPDATE] Following the publication of this story, a Microsoft representative confirmed that the Xbox 360 500GB hard drive will go on sale this month for $110 and that the 320GB unit should drop in price.
"A new Xbox 360 500GB media hard drive will be available starting this month," the representative said. "The Xbox 360 500GB media hard drive will be available for $109.99. We are working with retailers to revise pricing on the Xbox 360 320GB media hard drive to maintain market competitiveness, as we do on a regular basis."
The original story is below.
The hard drive will sell for $110, according to the product listing, which also says preorders will open "soon." Microsoft also sells a 320GB hard drive, though it goes for $130. It's likely that Microsoft will drop the price of the 320GB hard drive when the 500GB model goes on sale.
Currently, the Xbox 360 is available in 4GB and 250GB options. The Xbox One, of course, comes with a 500GB and also has support for external storage (as does the Xbox 360). In November, Microsoft will release a 1TB Xbox One console in a bundle with Call of Duty: Advanced Warfare.
The 320GB Xbox 360 hard drive, and presumably the 500GB unit, will be compatible only with the newer Xbox 360 S and Xbox 360 E models. We have followed up with Microsoft, asking for more information about the 500GB Xbox 360 hard drive.