Amazon is hosting one of their most commonly seen deals today, one for SanDisk memory with prices slashed by as much as 70%. You will find Ultra (speeds up to 30MB/s) micro SD cards with 32GB limits for as little as $14.99. They also have 64GB Ultra micro SD cards for $29.99. If you want similar amounts of storage but faster speeds, we are talking the Extreme line (speeds up to 45MB/s) which comes in 32GB and 64GB sizes as well, with prices running $20.99 and $44.99, respectively.
SanDisk did not include their 128GB micro SD card in the deal, so it will still run you $99.
Devices like the Galaxy S5, LG G3, and HTC One (M8) all supports micro SD storage.