Found some heavy duty kraft boxes at Hobby Lobby yesterday evening that will work well for stackable handgun storage. They carry many different sizes that will fit most combinations of pistol / revolver and barrel length. After adding some VCI paper, the total cost would be less than $3.00 (w/ no coupon) for most handguns. The box shown in the photo below was only $1.99 prior to using a 40% off coupon.