For the "do-it-yourself"er, or the budget conscious I've had really good results using wet foam from the local hobby store. This is the stuff used in flower arrangements.
I cut a small block, wet it with 50/50, put it in a ziplock bag open at both ends, toss it in the coolador/tupador and forget it for about a month.
Total supplies will run you about 10 bucks, and depending on how large you cut your wet foam blocks you can make 10 to 20 humidifiers........cheap!