Looking at this list of fast cards on blackmagicuser.net, I couldn't bring myself to spring for a 95MB/s $133 Sandisk Extreme Pro 64GB - so I bought an ADATA 64GB (95MB/s read, 45MB/s write) for $56 (on sale at Amazon) instead. ADATA, an established DRAM and NAND flash memory manufacturer from Taiwan, just entered the high speed SD card market a few months ago, so their prices are a little lower than Sandisk's. On sale, this card is a very good deal.
At 45MB/s write, the ADATA will be good enough for ProRes, but won't cut it for CinemaDNG RAW. When Blackmagic issues the RAW firmware update, I'll buy a faster card, but until then, this will do.