If you have hard water, an evaporative humidifier like this works well. It doesn't make white mineral dust like a cool mist humidifier. Mineral dust will clog a carbon filter.
If I were in your position, I'd buy a top filling $50 evaporative humidifier from holmes or honeywell with at least 1 gallon of capacity.
I have used various humidifiers for 10 years and have some thoughts. I have a piano, cello, several acoustic guitars, wood clarinet, and sensitive electronics that don't like static electricity so I keep my home at a constant humidity of 45-60 relative.
When it comes to humidifiers theres really only a few things to consider.
It needs to be easy to fill. Many have tanks that must be removed and taken to a sink to fill and the harder it is to do that, and the easier it is to drip water everywhere when filling, the more of a pain it will be to fill it up every single day, sometimes even more often. Get something with a large enough reservoir that it can go 24 hours on high without running out of water. You want about a gallon for every 350sq/ft of capacity. Many of the newer models now have permanent tanks and are top filling which is super easy as you just fill up a jug or something and pour water in the top. Much easier than fiddling with screw cap tanks.
How it gets water into the air. The only way to go is evaporative. Do not get steam or ultrasonic humidifiers. Steam uses too much electricity and it can over saturate the air leading to condensation on your instrument. Ultrasonic doesn't put out enough mist and it also puts mineral dust into the air which settles on everything as a fine white powder. You're also more likely to catch a bacterial infection from breathing in ultrasonic if the water isn't pure. Evaporative is the best because it is low power, and it self regulates. The more humid the air gets, the less water evaporates, slowing down and eventually stopping how much water it puts into the air. If it's really dry, it works faster, if it's only a little dry it works slower. IE always the perfect amount of moisture. Set it and forget it.
Wicks, Filters, and longevity. Evaporative humidifiers use a wick to draw water into the air where it evaporates. This wick is like a mesh filter and as water evaporates it leaves behind minerals which slowly build up. A wick is usually good for 1 whole season and should be replaced yearly. They are usually about $10. Using an old wick reduces the rate at which it can put water into the air but otherwise causes no problems. You want cheap filters and wicks that are easy to find on Amazon or a local store. That means sticking to brands like Holmes or Honeywell.
My current humidifier is a Holmes whole house unit with 2 external tanks and I've had it 5 years without any problems. Every winter I buy a new wick, and otherwise forget it's there. When I run it in winter I have to re-fill both tanks about every 24 hours or so depending on how dry it is. On low setting it can run several days. It's a pain filling the tanks as they are heavy, and have to be filled upside down in the bathtub (too big for a sink) and then carried right side up, so they drip a bit on the way back to the machine. It's otherwise perfect and large enough to keep my 1800sq/ft home humidified.
If you use a wicking evaporative humidifier like this instead of an electronic cool mist humidifier, you will not get mineral dust. The minerals will remain in the wick, which you will replace perodically.