Curious about this for my D40 - a good buy? Am I correct in saying that this is the only remote shutter release for the D40 (meaning that it can't take a cable release?) They're on eBay for 20$. And there's a knockoff one for about 3$ with free shipping. I think I'd spring the extra 17$ though. I just don't trust a listing with grammar of a fourth grader. Also, down the road, I'm looking to get a D90 - this works with that, correct? Thanks as always!