It's that time again, boys and girls: Amazon is having another massive Gold Box sale on SanDisk-brand memory cards and other storage mediums. Specifically for mobile devices, the SanDisk Ultra 32GB MicroSD (SDHC) card with a free card reader is just $21.99, a savings of 69% off the retail price. The 64GB (SDXC) version of the same card is $42.99, 57% off the retail price of a hundred bucks. Both are currently in stock and qualify for Amazon Prime free shipping. The deals are valid for today, Monday, June 3rd only.
If you've got a more versatile device (or just need some storage for your camera), the SanDisk Extreme SD cards are also on sale.