Iceland is all about massive glaciers, black sand beaches, and steaming hot springs like the Blue Lagoon. The trick to doing it right is going during the shoulder season in late spring, when you miss the crazy summer crowds and prices are a bit more reasonable. For a typical week, you are looking at spending about $2800 total for flights, lodging, and getting around.
Most people do not drop that kind of cash on a vacation all at once. Instead, we break it down into manageable chunks so the trip actually happens.
Remember that the 18-month window is a hard deadline, not free money, and any leftover balance when it ends will start racking up standard interest.