NYC-London-Iceland-NYC for $403, Includes 2 Checked Bags

Icelandair and WOW are both low-cost airlines based in Iceland. Icelandair offers free checked bags, WOW charges for checked bags (and even for overweight carry-ons).

Here is a low cost deal from New York to London, with a multi-day stopover in Reykjavik, Iceland.

http://www.theflightdeal.com/2016/04/11/visit-2-cities-icelandair-403-new-york-newark-to-london-england-and-reykjavik-iceland-roundtrip-including-all-taxes/

This fare is available for September and October travel.