Groupon Goods is offering the 32GB Dane Elec Pro 200x Class 10 SDHC card for $17 and the 16GB for $11. Free shipping with an order total of $20 or more (eg, two memory cards). Free returns and one year Dane Elec warranty. Limit 3 cards and two more as gifts for other people. It takes around 7 business days to arrive. Offer ends by 3/4/14 at 1am ET.
On the other hand, you can get the 64GB Dane Elec Class 10 SDHC card (DA-SDHS64G-C; up to 60MB/s read and up to 35MB/sec write) for $35 at Amazon by Amazon itself.
Speaking of memory cards, the waterproof+shockproof 32GB Samsung microSDHC Class 6 is on sale for $17 with free shipping by BuyDig on eBay (limit 5 per buyer).