Sure you have the mobo and other stuff to add to the price, but then again that GPU based rig is more flexible in that it can mine other alogs, including new ones that may come out. Also, as others have pointed out, the GPU rig can be parted out and resold if need be, whereas the ASIC is just a paperweight.
I used to think this way.....until Bitmain started going after the 2 main algos that gpu's mine with (cryptonight and ethash).
You can already see word of a 51% attack with ETN in the news lately.
I wouldnt be surprised if equihash is next...nothing is asic proof in theory and Bitmain has the funds to throw at to make it a reality.