Many years ago now, I published this video that covers my experience buying and using a K40 style laser cutter for the first time. It has honestly been a workhouse of a machine with little to no problems, though for such a low price tag, there are of course some compromises on build quality, safety and usability. Are these things enough to justify the cost? I think so, if you are willing to put in a bit of time and effort troubleshooting on your own and upgrading a couple of things along the way.
If you want to cut to the chase, here are some of the items that I would recommend to get the upgrades and extra items you may need to get cutting as soon as possible. Purchasing things from those links will cost you nothing extra, but help keep this channel active with project and tutorial videos as often as I can make them. Thanks!