GiveWP Dwolla Gateway Addon GPL Overview:

Now, integrate Dwolla’s payment gateway into your website, which allows you to accept donations with no percentage fees, although it only charges 25 ¢ per transaction or is free for transactions of USD 10 or less. This is the cheapest payment gateway with a minimal fee structure; no SSL certificate is required as the payment is recorded by Dwolla on its interface. Setting up the plugin is very easy and only takes a few minutes.