It's difficult to say. You usually get great saving from the Refurb Store when you're buying products that apple no longer sells as new. For example, on the Australian Apple Refurb (I live in Aussie) store there is a MBP that has 39% off the original cost price. Also with refurbs the chance of you getting a faulty machine is less, and there is also a chance of getting extras that weren't mentioned in the product description, e.g. More RAM, larger HDD.
Hope that answers your question.