This is my non-technical answer for you.
The cost of computer processors has obivously come down in price and up in power; many people don't appreciate the increase in storage availability and the decrease in price as well.
So any SD card will work in your Thrive. I'd recommend sticking with a better known brand of SD card (Kingston, San-Disk etc) as they tend to be of better quality and don't have issues down the line. I've purchased cheap no-name micro SD cards for my DINC in the past and I've ended up regretting it when the mSD card went bad after a time.
I found a great deal at Ben's Outlet for a 16GB class 6 SD card for $14.99. Picked up two, one for my Thrive and one for my camera. The Class of the SD card determines how fast it operates. The type of data that is written to the Thrive doesn't require super duper fast read/write speeds so I didn't bother with a class 10 SD card. 6 is more than sufficient for me.
Hope any of this helps.
