Why is some flash memory so expensive?

I was looking at flash memory yesterday and was fascinated by the differing price between different flash technologies, for instance if you were to purchase a 32GB Compact Flash card, which at the time of writing is around £140 for a Sandisk branded one, yet you can get a 32GB OCZ USB flash drive for £60 or even a 64GB one for £110!I seriously doubt it’s because of the performance, there probably both roughly the same, I also doubt that it’s a physical size issue as if you’ve ever opened up a USB flash drive you will find the flash memory is smaller then a compact flash card anyway.

Is it supply and demand? Maybe, I can only speculate, but I can’t imagine the demand for large USB flash drives being as high as the demand for large Compact Flash cards that are used all around the world by professional photographers and video production companies alike.

So why do large capacity Compact Flash cards seem so behind USB Flash memory?