Just a thought on lens selection:

Zooms

Tokina 12-24 f/4 (3.01 at photozone.de) (around CND$500 used on ebay)

Sigma 24-70 f2.8 (2.67 at photozone.de)  (around CND$500 used on craigslist)
Canon 24-70 f2.8 L (4.24 at photozone.de) (around CND$1300 used on craigslist)

Canon 70-200 f4 IS ( CND$1150 on craigslist)

This would cover  quite a wide range with 3 lenses.

Primes

To get the really large apertures, primes seem to be the only way to go.

Canon 100mm f2.0  (4.19 at photozone) (CND$425 on craigslist)

Canon 50mm f1.4 (4.19 at photozone) (CND$400 on craigslist)

Sigma 30mm f1.4 (3.06 on photozone.de) (1/2 the price of the Canon 35mm f1.4 with arguably better wide performance then the canon, but sigma lens is only for crop bodies) CND$400-500 craigslist
Canon 35mm f1.4 (3.74 at photozone.de) (CND$1350 on craigslist)