http://store.summitracing.com/partdetail.asp?part=DRT%2D11320010&view=2047&media=2

Check Ebay, there's a seller "racepartsdirect" whose selling them cheaper with valves and valve springs installed $899 "buy it now price" for a pair. You tell them what cam your running and they'll install the right springs at the right height for you. Depending on what your building for a motor, you may want to go with 215cc runners...racepartsdirect sells those also for a little bit more.