i think the union-pearson express train ( https://www.upexpress.com
) is between 30-50ish dollars, depending on where you want to get off. there are also coupons around which could cut that in half or so, if you found one! public transit is much cheaper, but takes more time (more than an hour).
even with the travel into the city core, you'd still have lots of time! it's a great city, with lots to do (and eat!).