Get two car booster seats for approximately the price of one: $15/each including taxes.
http://www.canadiantire.ca/en/pdp/apramo-child-booster-seat-0466045p.html#.U6ci4RCfhj0.
http://reviews.canadiantire.ca/9045/0466045P/apramo-apramo-child-booster-seat-reviews/reviews.htm.