does anyone no if sony will give me one for free?

I don't think its that big of a deal. I bought a controller and used the same usb cable to charge it. I Charged one after the other. The cables don't cost too much. A good thing is that the controller came pre-charged so no worries about that until later. Charging doesn't take that long so you can charge one while using the other (or however many you have). As for why it doesn't come with one, Sony is trying to save money but just listen to what I said and it shouldn't matter.

well it comes with one when you buy the system, also USB A to mini B cables are very very common and come with many devices from usb hubs to external hard drives, even many video and digital cameras. u can buy them at stores for around 10-20$

its just another way for sony to rob you

Because it costs money and Sony are being cheap about it. The system came with a USB cable so use that one. Sony won't give you one, but it never hurts to ask.