PayPal charges 3% plus a small fixed transaction fee for US transactions and the fee is paid by the recipient, i.e. the Friends. Credit card merchant fees are normally around 2%, depending on volume, but if the card you use gives you miles or money back, then the fee to the merchant is 3% or more. If you are a serious supporter of the narrow gauge, by all means send a check.
Accepting credit cards is a smart idea though, as it allows folks to donate on impulse. Dial the phone, read off some numbers and you can feel good about having done a good deed! 97% of a donation is a whole lot more than 100% of a donation not made!
Michael Allen