I am not sure if you are familiar with our "Terms of Service" so let me provide an extract of it:
The developer level account allows for unlimited usage in client projects, it does NOT allow for redistribution of templates in any form. If you have questions regarding this distinction please check with the FAQs or contact us using the Contact form.
You may not place any non-GPL portions of our products, modified or unmodified, on a diskette, CD, website or any other medium and offer them for redistribution or resale of any kind without prior written consent from RocketTheme. Please contact us if you require more clarification
As you can see, we don't allow reselling of our templates, extensions or anything else we provide to our members.