I've never seen the need for a specialized multimeter and have used my Micronta digital multimeter for years.

The small handheld glow plug starters are handy and the voltage is usually right for most glow plugs. They are I suppose especially nice for firing up your average B-36 model with 6 engines and a 12 foot wingspan but offer less advantage for a single engine model particularly with an electric starter requiring power from the field box anyway.

Glow starters that plug into the power panel on your field box are nice in that you run off your 12 volt starter battery and never have to worry about charging them or having one go dead in the field. You can also adjust the voltage to get exactly the right glow plug temp, which I like. In my opinion the important thing with either type is to get one that locks securely on the glow plug and will not fall off as soon as you spin the prop with your starter. That can be really annoying.

I think the gizmo they sell at the hobby shop IS the cheap way to balance props. The question I think most people would ask is how badly do you really need to balance your props.