Since you mention disposable income, if you can tolerate in-ear monitors I would suggest getting custom-fit silicone IEM. Used with even a very low level of music (or even some white noise generator) they dampen noise like nothing else in my experience. Successfully tested in a work environment with endless yammering, bleeping computer equipment, that mandatory 'shout-speaking' colleague, and even once a guy who let a 1U server running on his desk for a week for testing purposes (because why not).

The only down-side for me was that they are not as quick to pop on and off as regular headphones.