Technically--yes, the price is cut-and-dried.
However, depending on where the typical price in your area might be at this time (I haven't shopped for a new ST in some time, so I really don't know how typical sales prices are comparing to X-plan prices these days), you may be able to use X-plan to still negotiate a better deal. If you walk into dealership A, and say, "I can get an X-plan price on this vehicle from dealership B, but I'm willing to work with you instead if you can beat it by $xxxx, otherwise I'm ordering from dealership B"--and you actually mean that and follow through, the worst you'll do is the x-plan price.