In the past few years we have seen a strong trend towards 'Buying Local' (i.e., farmers market) as people realize that this helps boosts the economy. Supporting local businesses means that the money stays more in the community.
A study was done by the New Economic Development on the impact on buying from local markets or Community Supported Agriculture (CSA) programs versus a supermarket. Findings showed that twice the amount of currency stayed in the community when buying local.
Another reason for supporting local is to provide more people the benefit from these purchases causing whats been termed currency circulation velocity. The money goes back into the input of goods and services which usually goes back into the hands of locals.
Lastly promoting local promotes innovations as products are catered to for example a certain climate or community that may not be appropriate anywhere else, not always is there a one size fit all situation.
Even though local products may be more expensive it creates jobs for local employees and less harm on the environment (i.e. transportation). Promote Local.