A couple of thoughts...
... sometimes, it's not the mouse, but the surface the mouse is on. Are you using a mousepad? Try a different one, or try using one. I don't like the plastic-like ones; I prefer a cloth one.
... at CompUSA today, I saw basic mice selling for around US$2.97. That should almost make CA$5.83, before the tax
Do they have CompUSA in Canada? Or is it CompCanada?
Whatever, check out store prices. You may be surprised.