Originally Posted by JeepinJordan
.. one spun spun spun and broke inside the block...
And thus the importance of using a torque wrench.
Ok, you broke a bolt off inside the block. IF you have room for the drill motor, I see no reason to remove the oil pan. Metal chips from the drilling can't get inside the pan. Now for the hard part... drilling out the bolt.
You use a bolt smaller than the bolt size; you don't want to get into the threads. I have had good luck using a left-hand carbide drill bit Carbide is very hard, but brittle. Don't bend it! You won't find this at a hardware store; look in a machine supply house (msc-direct.com) The problem comes from the fact that bolts never break off leaving a smooth, flat surface. It's always at some angle, which makes drilling straight down the center of the bolt. Go slowly and watch what you are doing. Wear safety glasses; the chips will fall into your face....
Most of the time, the left-hand drill bit will, at some point, grab the bolt and spin it right out. If it does, you're golden. If not, well... now it's time to reach for the screw extractor. The problem is the typical extractor really sucks; they expand the bolt which is exactly what you don't want. Try to find an extractor with a shoulder. It will screw into the bolt only so far, then usually pulls the bolts out.
You can also try the idea of the left-hand tap. They grab the drilled bolt, but don't expand them like a screw extractor.
Obviously, this is going to take some time. Be patient, and do it right. Oh, as for where to buy a new bolt... why not the dealer? And just a thought, if you broke one bolt, you may have over-tightened all of them. I would replace all of the oil pan bolts.