Good alternative for BOSE Quiet Comfort 2 noise canceling headphone???

Hi,

I need a headphone which is:

1. really good in noise canceling;
2. comfortable, as I may need to wear it for sleep.

The BOSE Quiet Comfort 2 noise canceling headphone has been recommended. However, its £225 price is a bit too much for me. Can someone please recommend a good alternative at a reasonable price?

I have looked into Sennheiser's products. A search came out with the results of IS 380, RS 110, RS 120, RS 130 and RS 140. Which will be most suitable for me?

Thanks really for your help.