I was considering the rental dress/photography package as well, but after checking a few studios I personally don't think you can save a lot with the packages - it's cheaper to have the dress and photography separate.
So many rental dresses I've seen have minor flaws like loose beads/sequins, stains, etc. because they've been worn more than once.
If you're like me, who can't justify spending a fortune on a dress I'll only wear once and not too picky about dress style, I'm sure you can find nice dresses for under 800.
Apparently there's this store called Action Liquidators, in Renfrew.
http://www.actionliquidators.com/
I know the website doesn't look promising but I plan to still check it out. Will post update after visiting.
Also check Bryan's bridal gallery in the Brentwood Mall, I saw quite a few beautiful dresses there~
Hope this helps!