Standard Open Source Customization Rates

Hi friends

I would like to know the standard rates for open source customization that IT companies are using. Please share your thought for open source like

Wordpress theme customization
Magento theme customization
Oscommerce Template Design
Joomla Template Design
CMSMS customization

And any other if you would like to share.

PLEASE DO NOT SHARE FREELANCER'S RATE.

Thanks in advanced