Cheapest/easiest way of heating is a cheap aquarium thermometer sanitised and dropped into the wort. I was doing this with 1,000 litre batches for most weekends of last year (I had 12 months part-time professional brewing) without any issues*. They have rudimentary thermostats built in (so you don't cook your guppies) but controlled by an Inkbird is even better. If you can find somewhere consistently too cold, keeping a fermenter warm is easier than keeping a fermenter cooled.
*That sounds like I'm a very experienced brewer, I'm not, I watched a Youtube video about dry hopping this morning because I've never done it. However, what I have found is that as long as you follow the basic rules, to the letter, simple brewing isn't difficult. In fact, it's simple.