Hey Cam,
The best place to go in town is to Wholesale Bevel and Edge. That is where I had them drill my glass and cut it as well.
http://www.yellowpages.ca/business/A...?src=&stype=si
You do run the risk of the glass breaking. But chances are it won't. They will ask you if the glass is tempered. Hopefully it isn't. If it is, it will explode when then go to drill it. Most likely it isn't tempered. Most manufactured tanks (ie oceanic, all-glass) have a tempered bottom,while the side are not tempered.
Brad