Mattress prices fluctuate throughout the year, and there are typically dozens of sales throughout that time, but May tends to be one of the best times of the year to buy a mattress. Mattress retailers must rid themselves of enough stock to receive the new models, which means slashing prices until all their ‘old’ inventory is gone. Memorial Day is celebrated in the merry month of May, and Memorial Day weekend mattress sales tend to be the most lucrative for consumers.