Update:
Bought the Pirelli Pzero Nero GT tires from SimpleTires in the states, since no place in Canada offered this tire in the sizes I needed.
SimpleTire offered the cheapest price for the set compared to TireRack and Discount Tires (price match, but out of stock for the front tire). I waited until there was a sale on the site and combined it with the Pirelli rebate.
The staggered set in 215/40-17 and 255/35-18 cost me $631.58 CAD. I also bought a set of used wheels from someone in the states so I picked them up from my mailbox on the same trip.
Total cost for tires and miscellaneous expenses in CAD:
tires: $631.58
gas: $32.79 (roundtrip Toronto to Niagara Falls, NY (1.5 hrs 1-way). Drove a V6 SUV, if I had driven my daily corolla it would have been less)
lunch: $46.56 (fancy McD's lunch with fam)
toll bridge: $4.75
family roadtrip: priceless!
Was honest with the CBSA officer on return and luckily did not have to pay any duties or taxes.
