Yes, wheat starch is readily available from <i>fuya</i> (gluten-makers) as a by-product. I'm not sure but I think corn starch is an Americanism for wheat starch - in other words they're the same thing. If you're after the gluten from a wheat source Canadian wheat has been preferred in the past because it contains a higher gluten content.

My own little extraction experiment was just to see how the separation process worked. It's quiet a fascinating process; the starch is heavier than the gluten and soon sinks to the bottom of any water-filled container - it can then be cooked into a paste and used in the conservation process, or made into various culinary delights.

Towards the end of the Pacific War, Japanese conservators were allocated small amounts of wheat starch in order to make the paper balloons that were used a couple of times to 'bomb' the United States (they only ever succeeded in killing a dog). Food was in very short supply however so a few Japanese conservators actually ended up eating some of the starch! Had the Japanese been quicker in developing the bacterial agents they were working on, however, the result could have been a lot nastier - that's another fascinating story but way off topic :-)

If anyone's interested you can buy various fu products from the Japanese (and probably Chinese) food shops in this country.