i checked with the Argos for my brother’s reception. they are not priced too high but i think they had issues with us catering the food, although i can’t remember 100% now. either way, i wasn’t impressed.
i haven’t checked with Heintzman House but if you are looking for an outdoor wedding at an estate, check out Graydon Hall and Parkwood Estate too. Parkwood is in Oshawa and i got married there- its so beautiful the compliments still keep coming almost 3 years after the day mA! plus in Oshawa means its much more reasonably priced than a Toronto venue. Graydon Hall is super super expensive but also beautiful.