Karaoke systems range wildly in configurations and prices. You can get a basic unit for personal use that has a built in monitor, speakers, and karaoke player or you can invest in something a little more professional. What you need really depends on how you will use it and how into karaoke you are. If it is a passing fad for you, then I’d suggest one of the personal all-in-0ne units. This is also the best option if you are looking for a karaoke player for a child. My niece got the Frozen karaoke machine for Christmas and loves it!
If you want to be able to host more professional shows, you will want something that lets you change keys, tempo, has a sound mixer and more.
These are some good stores where you can find karaoke equipment. I’ve shopped at some, but not all of them.