Never been a fan of any domain with a number in it.
We all know that single-character .ca domains don't exist. But if I was to tell you verbally "oh, go to five.ca", I can guarantee you that a large percentage of those told would attempt to go to 5.ca. And see nothing. And become frustrated.
If I had to pick a number, five would definitely be one of the better ones to pick, but the $4.5k could have been spent way better, IMO.