The way to help Berserk financially is by buying the manga. The reason the releases are slow these days isn't because of lack of money, it's because the author is taking time to make sure the series is up to his very high standards. Berserk is a very successful manga series, and its author, Kentarou Miura, does not have any money problems.
As for financing another anime adaptation... First off, I don't believe a Japanese company like Hakusensha would like the idea of crowdfunding, second, the sum required would likely be very high, and third, if I were to pay for it, I'd want to be absolutely certain that it would be up to my standards of quality.
Patience is the key here. Accept that you will not see this story finished for several more years, but when you do, it will be well paced, thought out, surprising but ultimately satisfying, not to mention it will look amazing. Some things can't be rushed or sped up no matter how much money is thrown at it. You can't birth a baby in 1 month with 9 women.