Parker G2 style refills aren't pressurized, but they're pretty decent.

Casio make great functional clocks, if a bit ugly.

They also make wristwatches with hourly chimes that are loud enough. An F91W is like $10.

MDR-7506 from Sony is in the same range as the M50X price wise and is world-renowned and time-tested for being able to take a beating.

Also, might be worth looking into IEMs instead of headphones.

Sennheiser build quality is okay but not incredible. You can take a peek at HD280s though.