Mine is from Green Air, purchased through Puritan's Pride for just under $20. It had good reviews and I'm not disappointed. I didn't want to spend a lot, either.
It also has lighting options: four different colored lights that can be turned on individually or turned on where the different colors swirl one after the other. You don't have to use the lights, however.
The only issue I've had with it is finding a large enough spot where I can lay down a large enough protective covering: the mist is very fine but it is mist and will collect on furniture.
If you have a larger area/room you'd like to "mist," you can take off the top piece (the diffuser). I lost that piece so that's my only option, which has complicated the placement of it.
The tank doesn't hold much water, so depending on how long you'd be using it, that might be a factor for you. If so, you could check to see if it comes in a larger size.
(Pray you don't make the mistake I did...I thought I grabbed a bottle of essential oil when it was a chemical-laden, scented warming oil someone had given me. I had the mister going in my bedroom while I was bopping around the house--and BAM! I started losing my breath, couldn't stop hacking. Hours passed after I unplugged it and it was time for bed, but I couldn't sleep in the bedroom that night. What a derp.)