Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
This is a product I am waiting for as well. I like the idea of thunderbolt better, but don't want to pay the massive premium vs USB 3.

One option is to use an express card thunderbolt adapter with a compatible USB 3 card, but not only is it expensive, I believe mountain lion broke the drivers for the USB 3 chipset that the add on cards used. (Someone else with firsthand experience will hopefully confirm or refute this.)

Now that USB 3 is a reality on osx and recent macs, hopefully someone will build a thunderbolt adapter for the older models soon.
 
So i guess there a no cheaper alternatives available right now? :(
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.