As you'll see below, I came across them at More Than Ink. They offer the option of buying both punches as a set at less than the cost of each punch purchased individually. That's where I bought mine. I've also seen them available for preorder at Frantic Stamper. Fran also had the instructions that I thought should have come with the punches, so that's worth a look. I didn't realize that the corner punch is designed so that it can also be used to punch an interior corner of a card front. I'll have to check that out. By the way, I'm comfortable mentioning both of these vendors here since I've had good experiences with both.
I haven't seen them at any bricks and mortar stores that I frequent, at least not yet. It'd be great if they do start showing up at places like Michael's. Each punch costs about the same as the usual edge or corner punch, so a coupon would be great to use. I've clipped some of the other designs to show you as well.
Hope that enables you just a bit more! ;-)