How do I reduce a product price if people buy 3 of the same unit?

Hi,

I'm opening a bulb online shop and I would like to give my costumers a reduced price if they buy 3 of the same item. 

How can i add this option to my e-shop?

Thank you very much

Yes, I would also want to know if there's a solution or workaround for discount when items are bundled. 

@JoGutierrez is this something you can help with? There are many variations of the same question floating around forum.