It ain't cheap....
SanDisk unveils 512GB Extreme Pro card: Digital Photography Review
SanDisk has announced the latest addition to its Extreme Pro class of memory cards. The 512GB Extreme Pro SDXC UHS-I is introduced as the world's highest capacity SD card, supporting 4K video with write speeds up to 90 MB/s and UHS Speed Class 3 recording. It can transfer data at speeds up to 95 MB/s. The 512GB Extreme Pro SDXC UHS-I card will retail for $799.99.
SanDisk unveils 512GB Extreme Pro card: Digital Photography Review