I walked all the way through checkout (stopped short of buying) and it kept the price at the lower sale price all the way through. Are you saying it changes once I commit to buy?
it will give you an error and tell you there is a problem with items if you submit it. this happened to me last refurb sale. i had a 70-200ii in my cart from a few days prior. i was ecstatic until i clicked submit order, and then i was heart broken.