If you need to take payments over the net it could be difficult setting up your own system.

I would have a look at Paypal. They do a 'donations account' that allows you to take all sorts of payments over the net with credit cards or other paypal accounts. I would guess that the donator would have to enter their details as well so you could use this for people you need to contact.

It's secure and people know the brand as well. Worth a look.