The savings from domestic drilling or mining isn't the point. It's not even in question as far as I'm concerned. The problem is it isn't sustainable. We can drill and extract coal and petroleum many many times faster than the formation of new deposits. Doesn't take a math major to figure out what happens when the magnitude of the output is greater than the magnitude of the input. Any savings from domestic drilling would be temporary. And decades down the road we'd find outselves back where we started, or worse.
We also never would have made it to the moon or won WWII without accepting financial costs and risks in developing technologies that we weren't even sure would work to begin with. Alternative fuels could potentially be cost effective as we work to develop better processes in their production. Of course on the flip side, it would be nice if environmental activists would back off a little and let the scientists and engineers work the problem rather than trying to ram things down people's throats.
"Don't confuse facts with reality."
-Robert D. Ballard