The issue is part interface, part bus. Most hard drives out there simply can't read/write data as fast as the thunderbolts can throughput it, unless they are SSD's or are in a Raid 0/5 configuration. So it's no surprise that the only two drives "on the market" are the Promise Pegasus R4/R6 and the Lacie which is a two-drive Raid 0 setup. It also costs tens of millions of dollars to adapt a new connector to an existing drive, so the up-front investment is fairly substantial for the vendors, and there just isn't the user base yet.
Personally, I think $150~200 per 1TB is not a bad price to pay for performance that's 10x faster than FW800, and that is what Promise Pegasus is charging. As a photographer, however, I still need a portable drive and I don't mind if it is slower than optimum speed; anything greater than FW800 would do for holding and editing large amounts of data while traveling (my MacBook Air only has a 256 GB SSD drive and half of that is already 'taken')...
Don't worry. I predict that within a year, some of the high-end cameras will have TB interfaces built in so you can jet your 64GB card over to your MBA in just 30 seconds...