most noise cancellation headphones will do noise isolation as well (so that the cancellation can be more effective). On/Over-the-ear will typically give you better noise isolation than earbuds
I have a pair of relatively cheap (<$40) Sony earbuds, they work well enough on buses/trains/airplanes:
http://www.amazon.com/Sony-MDRNC13-N.../dp/B004P7O26W
I think the gold standard is still the bose QC series.
bose QC 20 earbuds, ~$300 , or QC25 around ear, can probably hit $200 during holidays.
these Audio-Technica earbuds are relatively cheap($40) and have decent reviews too :
http://www.amazon.com/Audio-Technica.../dp/B004K09H32
do remember that active noise cancellation CAN affect the audio quality. best is to just use noise isolation to block most of the unwanted sound. also, active noise cancellation usually requires an external power source, need to remember to charge battery too. if you want, the sony Xperia Z2/Z3/Z3compact phone line has optional noise cancellation earbuds that draw power from the 3.5mm jack, dont need to charge a separate battery