Looking for a budget solution from Europe to Canada consider this solution with Canadian low-cost carrier WestJet. Return flights from Dublin to St. John´s in Newfoundland & LabradorNewfoundland & Labrador are available alredy for €189, Halifax from €210 or Toronto already for €252. Note that this fare includes hand luggage only, checked bag is available for additional cost. Though you would have to be a bit flexible as very limited travel options are avialble in September and October 2016... We are also adding some interesting open jaw flights from Ireland and returning back to UK (London, Glasgow) already for £159..
Need to find lowest fares available simply follow to WestJet website and use "Flexible dates" seach. There are few travel options to St. John´s and Halifax but seems only one outbound date to Toronto for said price. so hurry up if interested in this budget option to North America..
Booking samples
Booking sample of a cheap return flights from Dublin to Canada from €189 here. In this case you would be departing from Ireland to Halifax on 4th of October. Your return flight from North America back to Europe would be then on 18th of October 2016.