Whats the most cost effective way to get more power out my Supercharged V6 Commodore S.It is all standard, so I'm looking for some advice and estimated pricing.

Given you have a L67/factory supercharged V6 Commodore, there are heaps of upgrades which can be done as shown in the link below.

http://support.maceengineering.com.au/Knowledgebase/List/Index/143/l67-supercharged-performance-kits

Considering you're starting out, the package below would arguably represent the best value for money for you.

http://support.maceengineering.com.au/Knowledgebase/Article/View/96/143/1-l67-supercharged-budget-package