B&H has several Sony SD cards on sale right now, including the Sony 128GB UHS-I U3 SDXC card for $54.95 (reg. $76.95).
The U3 rating (also known as a Speed Class rating) is important for capturing high data rate video like compressed 4K or a high speed frames found in cameras like the Sony RX100 IV and Panasonic GH4. For a better understanding of memory card specifications, see my earlier article Demystifying SD Cards.
You can also pick up a 256GB U3 card for $128.95 and a 32GB U3 card for $14.95. These deals are good through October 20. Check them all out here at B&H Photo.