Heya,
I picked up a light meter a while back after researching it and getting advise in the lighting forum, and it really was a game changer for me. While I already used my in-camera meter and learned my meters to each camera as they all behave a little different in terms of the outcome, and I was able to generally get what I wanted out of it reliably, the light meter adds a whole new depth to it. Granted, I don't just do natural light, I use mine a lot with mixing ambient & lighting and that's where it really comes in super handy to take out the guessing factor, and being able to incorporate two exposure values into a single exposure. A basic light meter can help you dial in natural light and/or just lighting. The more advanced meters can do more functions, like ratios, and different blends and different kinds of metering. You'll find landscapers using light meters with spot meters to basically measure the dynamic range and know where to be exposure wise to get most of the range into their single RAW exposure. Same can be applied to portrait, etc.
I picked up a Sekonic L478-D, used, on Amazon for about $250. The warehouse deals are great. I would shop for a 2nd hand or refurbished meter to play around with.
One of my favorite tools, really made a difference in how fast I could get to a good exposure with unwilling subjects (ie, 2 year olds!).
I love being able to meter the ambient scene, then meter a light, get a blend and set everything, without ever actuating a shutter on my camera and getting it right the first time. It makes shoots with the kids so much faster and easier for everyone.
Ex:

IMAGE LINK: https://flic.kr/p/KbUY7n
IMG_4014mark
by
Martin Wise
, on Flickr
Very best,