I use a water bath with aquarium heater in the winter. I use these
and it works pretty well and does get down to 65 or 66F, which is usually low enough for me.
The important thing to note is you need to add motion to the water or the water will only get heated right next to the heater and then the heater will shut off and not heat the rest. I tape my stir plate (computer fan with magnet) to the side of the tote and face it directly at the heater. Yes it doesn't look that great, but it works very well. I also add a few drops of bleach to the water to stop bugs from growing and it works well. I usually only use it for the first 7-10 days of fermentation anyway. Hope that helps.