I get what you're saying, its weird when the Porsche is cheaper than the Ford. But Porsche might as well be the Honda or Toyota of the racing car market, while Ford is the McLaren. Due to the thusfar limited run of the GT350R-C and the fact that its based on an engine package that is new to Ford and unique to the car, there was likely a lot more development that went into the car because so much is new, and it doesnt have the volume to make up for it.
Porsche meanwhile, has a very well established customer racing channel and is essentially using tech that isnt that far different from whats been used in Porsche sportscars of yore over the last few decades. And the model has the global volume to mitigate the costs. (And thats not even counting the GT3 Cup, R and RSR).
From what I understand, the Cayman does need to be further tweaked/modified to make it fully comply with IMSA regulations so I wonder if that price is before or after that fact.
Bottomline, Porsche treats its racing car business very seriously, while Ford, given whats been said about the GT program, considers it a marketing exercise. If they make money from the sales of racing Mustangs, thats fine, but they dont bother pricing them competitively because its not ultimately their goal.
