I mentioned this text to Kasim last week, but thought it might be useful for some of the other people who are doing the essay questions based around enquiry and analysis into your own economic situation. It's entitled Value, Price and Profit (sometimes entitled Wages, Price and Profit), and it's the text of a speech that Marx presented to the International Working Men's Association in 1865. It's worth looking at, as he's trying to outline the essentials of his ideas in an accessible manner, and in a way that would be of use to people concerned with understanding their own circumstances.
Perhaps I'm being completely stupid, but I couldn't find much Gramsci at all on the internet; the Marxists.org archive just seems to have the contents of his works and little else. If anyone else can find something online please do post it here.