I did two recipes of an APA. Both 10 gallon batches. The all grain was one I had just made and the other was an extract version, assuming $2 a lb for DME. The all grain cost was $18.43. The extract was $28.90. But in a quick look today I couldn't find DME for less than $3 a lb. So that would raise the price to about $34. That is my take on the OP's original question.
But as some have said here, its not about the price of beer that drive the move to all grain. For me it was taste and really feeling like I had a craft. Like the difference between assembling a kitchen hutch from a box or building it from scratch from lumber. And please all you extract brewers don't take offense to this. This is how brewing beer makes me feel and has nothing with how you brew or the quality of what you brew.
But as some have said here, its not about the price of beer that drive the move to all grain. For me it was taste and really feeling like I had a craft. Like the difference between assembling a kitchen hutch from a box or building it from scratch from lumber. And please all you extract brewers don't take offense to this. This is how brewing beer makes me feel and has nothing with how you brew or the quality of what you brew.