I'm using LEDs for the first time and the hum...

A humidifier would do the job u can pick one up quite cheap but if that's not an option I use to spray they tent walls and leave a bowl of water in the tent that would help along with foliar spray

There a couple cheap ways that do not involve buying a humidifier. Use less exhaust and put a wet towel inside the grow space. Also, once you go into flower the low humidity will be a plus, I would not worry, I would much prefer a low humidity environment.

unless you want to get an evaporative cooler , the only thing you can do is put a large shallow tray of water in front of your intake. the fan will suck up all the saturated air from the evaporation. Foliar spray works though, you can do it up to 6 times a day when the plant is younger. Now you're better off getting an evaporative cooler, small ones are like 40 bucks, large ones like you need are upwards of 100 ... otherwise you can get a mister, and it's the same problem really with the costs Hope this helps ! 🚀

You can pick yourself up a humidifier with a digital read and set to 50-60% but can get pricy. Or you could get a cheaper humidifier and pug into to controler with a probe. A cheap quick fix would be place a bucket of water in the growing area and the heat in the room will evaporate the water out of the buck but you won’t have any control at what percent the room is at, a humidifier is you best bet