I just bought an evaporative cooler. Here in arizona the humidity is about 10%. It is a portable evaporative cooler for $100, It not only puts humidity in the air, but it cools off my grow room just like an a/c unit. It's very cheap to run (about the same as a fan). The only thing is, It evaporates about 5 gallons of water a day into the air and it only holds 2 1/2 gallons in its resevoir. So I have to fill it up every morning and every night. Of course it's still $100, not as cheap as a bucket of water and a fan but it also conquers two tasks, humidity and cooling.