I recently purchased two SanDisk 8GB microSDHC Card - class 4(SDSDQ-8192, Bulk Package), for $39.58 each at Amazon.com. Amazon's supplier for these items is a company called DigitalMediaOutlet.com.

The micros came with a standard size SD adapter so I purchased the mini SanDisk adapters separately from the same supplier. The cards worked with no problems.

At one point during my vacation, my daughter's camera memory was filled and we still had a few hours of touring. I swapped the 8GB card out of my N810, put it in the full-sized adapter and used it in her camera. Later that evening I put the same card back in the N810 with no loss of my original movie data that I had on the card. I was also able to view the photos she had taken earlier that day since her camera had created its own folder on the card! The Sandisk media seems to be pretty tolerant.

I hope this helps.