There is something else only savvy business men know...
You can add a domain name purchase into your advertising account and write it off 100% but any really large purchase may be scrutinized by Revenue Canada so purchasing a 50k domain over 5 years allows you to write off 10k per year.
Technically you can depreciate any tangible purchase over 5 years anyways but digital purchases have their own set of tax rules so for some businesses a purchase over a few years may be desirable even if they can afford to pay for the domain in it's entirety.