I can work with you one this if you want. wrap the "Your total Registration cost" text in H2 tags. Also make the unsuccessful promo codes red as in "This code is expired" and the successful ones green as in "Discount Code Applied! You saved: $ 145.00". That's all I've got so far, but a little styling can make this a great component. It works very well now, but is plain Jane to look at.
I second the motion on styling. I think that there are some formatting issues in some places.
For example, in the upcoming events module, there is no control on how an event title appears. For my upcoming teleclass, visible at breakthroughcoaching.cc, the text is too large, is in gray and looks unattractive in the way the formatting appears. The title needs to be centered but currently there is no way to change that.
On the reg form, the asterisks for required fields are not aligned with text properly and when entering a longer label for a field, the text comes out spaced very weird as if it is trying to be left and right justified instead of just appearing as it is typed.
This formatting issue has forced me to get creative with my labels and questions but ideally I think this should be user modifiable.