Erindale sits among Saskatoon's established residential areas, and a two-family layout there usually appeals to a family wanting mortgage-helper income more than to a pure investor, which shapes who else you are competing against to buy it. That buyer pool affects both price and how quickly it sells.
The City of Saskatoon inspects a secondary suite for egress windows, ceiling height and fire separation before it counts as legal, and a buyer's own home inspection, typically $400 to $600, should confirm those items independently rather than taking a seller's word for it.
Legal status, not square footage, is what turns a two-family house into a financeable investment. Get your hand-reviewed valuation from Joel Dyck.