I saw that you have included the PayPal "Pay Flow Pro" gateway as a payment provider, which allows you to tie your integrated CC form directly with an Internet Merchant Account. The fees for that one are $250 to setup and $59.95 per month though.
Are there any plans to implement PayPal Website Payments Pro? That one is free to setup and only $30 per month. The difference being that the funds go into your PayPal account instead of connecting to a merchant account, but you still get the integrated CC form without leaving your site to pay. To me PayPal Website Payments Pro is one of the simplest and economical methods available to implement CC payment without leaving your site.