I've always wanted to get onboard with the Manpacks but it's hard to justify $10/shirt when I can get a 5-pack of the same kind on Amazon for $18.
For me personally, I'm cash rich, time poor, so it's a great trade off. I save the hour to go to the store, or find the best reviews on Amazon.
Manpacks curates only the highest quality products, so I pick from among the best.
You might be in a different place, but it's been a great value for me personally.
Shirts are a little different, but I use it for stuff like razor blades that are consumable.
Also, in a world of politically correct egalitarianism I respect a company that has the literal and figurative balls to stand up and say, nope, this is for men (and go so far as to bake that assumption into the product name)