The micro SD card I use with LeJOS is
Kingston 8 GB microSDHC Class 4 Flash Memory Card SDC4/8GBET
It is available on Amazon.com.
Many different micro-sd cards will work. This one has proven to be very reliable. I have created 24 installations with no failures.
You will need a blank SD card of at least 2GB and no more than 32GB. SDXC cards are not supported by the EV3 hardware. If you are reusing one from a previous version of leJOS EV3, you must delete all the files from it.
The SD card must be formatted as FAT32, must be empty, and must have at least 400MB of free space.