I have a non-profit website with only one product, a donation. The donation needs several different options for amount and an option for arbitrary amounts. It needs to integrate with paypal which should handle the credit card information. I would like to use Webform Pay module but it doesn't have a stable Drupal 7 version. Is there a Commerce contrib module that handles this?
Commerce guys created a nice screencast to show you how to do this in commerce. You can view it at http://commerceguys.com/blog/using-custom-line-items-provide-donation-feature-drupal-commerce
I have used this on pretty much every charity site I have done and it works well.
Here is a summary of the steps:
Condition: entity has field: field_donation_amount
Action: Calculate field_donation_amount * 100
Action: Line item: Set the unit price to value: calculated amount
Try this sandbox: http://drupal.org/sandbox/tmsimont/1891418
I could use a maintainer, but I'm using this on a production website right now. It's a little tricky to set up at the moment, but if it generates interest I might get more involved.
I would recommend getting them to sign up to Adyen payment processor, which enables worldwide cash deposits and other payment methods (Credit cards and paypal too) and has no monthly or setup fees. Greenpeace use them.
Then use this: http://drupal.org/project/commerce_adyen