>My card is a Verbatim 16GB "Premium" Class 10. >It was a freebie I got with the camera, >so it is possible the camera shop gave >me a cheap one.
You said it right. The Verbatim Premium Class 10 SD card writes at an average of 10MB/sec - the absolute minimum spec for a Class 10 SD card. For the kind of fast, fast write speeds we all want and expect when shooting, you need to buy a couple of 45MB/sec cards such as the SanDisk Extreme Pro. Transcend (the Ultimate UHS-I model, 85MB/sec) and Lexar (Professional SDHC UHS-I model, 600x or 90MB/sec) also make reliable, weather sealed SD cards in a variety of sizes (8, 16, 32, 64GB and larger - up to 256GB). The faster the card, the more they cost. Basically, anything 45MB/sec or faster will not hold you up at all.
The class 10 designation sounds like it should be fast out of the box, but the cheap cards often given away by merchants are usually the slowest made. The D3200 and all its siblings and bigger brothers write enormous amounts of data every time the shutter is pressed.