Are there payment gateways that only take a percentage of whatever money is paid, but that have a very small up-front startup fee?
I want to set up a payment gateway for a charity.
By the way - is there any harm in just accepting donations through paypal and avoiding the whole payment gateway hassle?
Many opensource projects use paypal for donations, I guess there is no problem with that.
Network For Good seems like a good bet. No startup fee and $30/mo + 3%/transactions fee. The company itself is a nonprofit, too.
For other suggestions...
http://nonprofit.about.com/od/faqsfundraising/f/creditcards.htm
Paypal doesn't charge charities the fees that other payment gateways will, so this is your best bet.