Imagine how you'd feel if your boss told you that he was going to cut your salary. You wouldn't be happy. That's effectively what happens when you buy a fake. You're taking money from the person or company who came up with the designs and invested money in developing the product. Don't encourage others to steal work that isn't their own.
Buying fakes isn't harmless, so don't rationalise it as buying something you couldn't otherwise afford. You're buying a poor imitation, not a good copy, and your purchase has consequences. If you really want a product that badly, save up for the genuine article. And beware of bargains - they're cheap for a reason. Have you ever been fooled into buying a fake?