this. As much as one can think, oh its just the psu, it'll be fine, some forget it is the one component that connects your PC with the 'power grid' - Personally I would not cheap out on a PSU. 1) nowadays GPU's have become super power hungry. 2) in case something does go wrong, a good psu can save your system from frying 3) low quality PSU's often don't have the best Wattage distribution over all the phases. 500W low end psu, may only give 380w on the PCIE connection.
So I in agreement with @Stahlmanndon't cheap out on a PSU.