Don't give me any of your namby-pamby BluRay or HD-DVD disks.
According to this Engadget article, InPhase Technologies are now shipping their first 300GB hologrphic WORM disks for $US180 each. Of course, you'll also need a drive to read and write these things. So far, I've not been able to track down the price for the Tapestry drive, but you can bet it will be many, many shekels.
The data transfer rate is 20 MB/s and they expect to scale up to 1.6TB per disk by 2010.