Bbedit-macportportfile-language-module is a project mainly written in ..., it's free.
A BBEdit language module for MacPorts portfiles
This is a BBEdit Codeless Language Module that provides good highlighting for developing MacPort portfiles in BBEdit.
Copy diff.plist into ~/Library/Application Support/BBEdit/Language Modules/). If no such folder exists, you may create one. After installing a new language module, you will need to quit and relaunch BBEdit in order to use it.