That's why I hate Cantilevers. I have a 2008 Tricross sport that came with Tektro mini V-brakes and they work great. Perfect modulation and stops on a dime.

You can get cheap Tektros starting at $20 or you can get pricier TRP Cx-9s for $100+ and both will be better than Canti's for stopping power.
The caveat however is that they run so close to the rim that it doesn't leave a lot of room for tire clearance and mud (if you race..) But road performance will be great.