Aer Lingus via DealBase discounts round-trip fall flights to Europe, with prices starting from $405.50. That's the lowest price we could find for select routes by $120. Book this travel deal by July 16 for travel from September 1 through October 31. Buy Now Tips On the DealBase landing page, click on "Aer Lingus" in the top line to see this sale; we found lower fares within. We found this price on flights departing on October 1 from Boston, MA (BOS) to Dublin, Ireland (DUB), with return on October 8. All prices, dates, and booking details were valid at the time of publication.