What if you don't know if you'll be able to make seek the peak until that weekend? Would it be possible to make a fund raising page and if you can't go, to donate your money to someone else's fund? Because when we to up north our money is tight so it depends up onto that weeks paycheck. I really want to participate but I want more to earn some money for the Observatory.
I'm not sure about that, but if no one answers you, I would ask here: http://www.mountwashington.org/contact/
Your best bet is to address it to Membership.
I certainly don't have the official answer, but the mountain is still open to the public so anybody can climb.
If you don't meet the fundraising goal then I guess you don't get a goody bag and you don't get into the after party for free. I suppose you could still pay the $15 and get into the after party. And of course you can still climb the mountain.
You don't have to make a fundraising page, many people do it offline. If I were you I'd either make a page online or register offline and see what you can do.