Edutopia published several articles about teaching financial literacy:
Financial Literacy: Resource Roundup is an excellent article with links to other articles about why teaching financial literacy is important. It also provides links to websites for teaching this subject to all grade levels.
Resources and Lesson Plans for Financial Literacy focuses mostly on the curriculum created by Ariel Community Academy. It has a whole unit on goods and services as well as other links to other resources around the web.
Financial Fitness for Life is another terrific website run by the Council for Economic Education (not Edutopia). Search by grade level, and all the resources are provided.
Revolution, Responsibility and Football: Teaching Financial Literacy to Middle Schoolers: This article has links to curriculum and websites geared towards middle school.