The cheapest way to go...

Purchase a plastic cooler 20 or so gallon cooler - get a tupperware container - put a piece of floral foam in the Tupperware container. Soak the floral foam with distilled water - pour out any excess water. Place the floral foam/tupperware container in the cooler along with the boxes of cigars. Close the lid. The humidity will remain right around 70%...

Total cost - somewhere around $40-50 (at the outside)...