Hi Emerana,
I personally wouldn't try to glue this. If it were some structural damage to the body of the flash yes, but that, that is the support for the flash itself. If glue it, it would just break again shortly after. The rest of your flash will act as a wrench and break it off again no matter how you fix it.
No, I would be thinking about a brand new hot shoe for you, possibly one from a cheap/dead flash - those should be cheap if you can locate one. The idea to send the flash to Canon is a good one in my opinion, whatever they charge you would be worth it as long as it is significantly less than a new flash. With some luck you might get your credit card company to either pay for the repair or pay for a new one (I have never used services like that, I am not sure how they operate).