The Inq heard at Computex that a 16GB flash memory based hard drive costs roughly $400 to manufacture, which is about 25 dollars per GB.
The price of a "classical" hard drive is just beyond any comparison, since we're talking about a little under two dollars per GB.
However, our two sources expect to see the prices of SSD hard drives falling really soon. A rough estimate is around $400 dollar for a 64GB hard drive with 20MB read and 20MB write speed by the next Computex. If the volume kicks in, the price would be halved, just down to a mere $200 for a 64GB hard drive instead.