I'd say forget about those models. I've heard a much higher-end Sony noise canceller (I just remembered that I had), and while the audio portion wasn't terrible (certainly not a prize, either), the NC was worse than useless. It actually amplified outside noise. This was the NC-60, which sold for $200 before it was discontinued. Something tells me if Sony has discovered the secret to a NC circuit that actually works, I highly doubt they've put the technology in something that retails for < $30.
Noise cancelling headphones as a class are fraught with compromise, are usually remarkably expensive given their level of audio performance, often don't actually provide much noise cancellation, anyway; and are seldom (if ever) a good value. If somehow the NC7 or NC8 broke that trend (actually obliterated would be a better term, at their price), there would be 3,409 different threads about the new Holy Grail of noise cancellers, and Tyll Hertsens would have posted an article on InnerFidelity about the newest headphone on his Wall of Fame.
Those things haven't happened, and it seems nobody who has heard these things has seen fit to post up, so I'd say pass. If you want something that actually cancels noise effectively, you're going to have to spend a lot more, or else get yourself a pair of IEMs.
Not that this is going to do the least lick of good, but you know, I'm bored and it's a nice evening so I'm in a decently good mood. I also didn't think I'd ever get a chance to talk about the NC-60 on here, so now I can cross that off my bucket list.