You don't need to feel guilty about spending your ca$h. Just don't spend it on products that were manufactured in a sweatshop in a developing country. Do your research find out were products are made and who made them. Choose fair trade if its on offer. Make sure your office or school offers fair trade coffee or tea.
Check out this post I wrote a while ago. It lists all the fair trade Chocolate I could find in Australia http://idreamichoose.blogspot.com/2009/03/fair-trade-chocolate-shopping-guide.html
Also check out http://www.fairtrade.com.au/