External video cards with MacBook Pro? I need to connect two displays to my MacBook Pro, and I read a recommendation to use external video cards to accomplish this. How can I do this? Do I just buy a video card and some kind of case which can connect to Thunderbolt? I'd really like to use Thunderbolt as it's so much faster than USB2.0. 

Since I'm getting a 17" MacBook Pro, I'm also getting an expresscard port. Will I be able to do something with this? Cheap is the price I'm looking for. :)
The most supported option would be to get a pair of Thunderbolt displays and use those. Note that will black out the screen on your MacBook (source).

I don't think there are good cheap options out there.