This weekend (April 15 & 16) and next weekend (April 22 & 23), the National Park Service allows entrance to more than 400 national parks for free in honor of National Park Week. (Grand Teton National Park pictured.) That's a savings of up to $30 (at Grand Canyon National Park, the most expensive national park).

Of note, admission to most national parks is usually free; click here for a list of parks that offer free admission on these days only.