There are some online retailers. But, honestly, I find the best place is eBay. Many of the online stores overcharge. One online store I've heard mentioned by others I know is called 3000toys
Not S650, but I think Mustang 1/64 fans will be happy to know in the RLC line, the 2000 Cobra R is finally being done. This is a preproduction mockup. It will be in the iconic red.