Before you drill to extract the bolt. Try the penetrating fluid as recommended. Use a test light, awl or other sharp pointed tool and see if you can rotate the broken bolt. If there is enough of an edge where it snapped push on it, tracing it out to back the bolt out. Becareful not to damage the top few threads as you try to back it out.

Also Auto Zone and Advanced Auto have tool loan/rent programs. I don't know if the do extractors because of the potential for them breaking.