To be honest, I didn't think Princess Auto sold the diamond tipped hole saws that you need for bulkheads. I could be wrong though. But it used to be the case that they only sold the smaller drill bits and the like, things like what you could use on a Dremel and so on and there were lots of people who would use them to gouge out a hole for a bulkhead, and that's fine on 1/4" glass. I don't think I'd bother trying it on 1/2" glass, I can think of better ways to spend 8 hours
But, like I said it's been a few years since I looked for diamond tipped tools at P.A. so they might have them now.
Used to be the case that a decent diamond tipped hole cutter would set you back $80-120 per cutter. Nowadays you can get them for about $15-20 from ebay. These won't have the longevity that the more expensive ones have, but ... for $20, just buy another when you need to.
Last time I looked at mops.ca (mail order pet supply website out of Ottawa), they too had the cheaper hole saws (in the $20ish range) so you can order some from them too, if ebay isn't your thing.
You still need cutting oil and some means to hold the oil over the hole as you drill, but, I imagine these are not too hard to come by.