This tabletop humidifier/Air cleaner works pretty well. It is easy to fill with water. You do need to buy non-iodized salt (something I didn't have) to get the air purifier part to work. It is a very quite unit, and even has a sleep mode which is extra quite. Very nice control features, including fan speed and timer (2hr, 4hr & 8hr). Very simple to setup. I'm not sure how often the filter would need to be replaced or how much it would cost but there are directions to rinse it out periodically. 

I can't be 100% sure about how well it cleans the air as we are using it in a pretty big room but I do think I'm sneezing a little less than normal.