You get what you pay for. The bar was/is set by the BOSE QC2 and the new QC3. It's hard to believe how much they cut down on the jet engine noise but I found my old QC2's to be a bit too big to carry and also the sound was on the muddy side. I ended up eventually selling mine last year and haven't had the chance to try the QC3 but they seem to have improved on the sound and are of a smaller dimension than the old QC2s.

Over the past year I've experimented with many many different headphones and earphones of different designs, shapes and sizes ranging from a cheap USD $9 to a whopping USD $299 for the QC2s. And while none have been able to cut down the noise as the QC2 (and I assume the QC3) but at the end I decided to settle on two non-noise cancelling products:

The very cheap JVC gummy ear buds for USD $9.99 which I use for the gym and throw out every 1-2 months for hygenic reasons (Yes, I'm a germophob)

And another JVC similar to these Marshmallow in-ear buds but with a bit more sound isolation through air cushioning around the edges for I think about USD $29.99 at Best Buy brick & mortar not available online.

So basically at the very end if noise cancelling is the most important factor then go for QC2 (if a bit of bulk doesn't bother you) or the QC3 (if a smaller size is more useful for you and you don't mind paying the premium). You can also get AP miles on these I beleieve and try them out for 30 days too.

EDIT: I thought this BestBuy link would be helpful. This is their entire stock of headphones sorted from $ Low to $ high. It's good if you want to do some research but I recommend you check other sites such as Amazon before pulling the trigger on the more expensive models.