What do you want to make?
I had the use of a Laser cutter engraver when i worked as a school D&T technician, I used it nearly every day.
First thing to know there are two basic types of Co2 Laser commonly available, DC watercooled & RF air cooled. All the cheap chinese lasers are the former, Laser Tube life is often very short, weeks or months typically 1000 hours max though some may go a lot longer.
We had a Lotus laser systems 30w RF air cooled machine, the laser tube is metal cored & can be regassed when its spent, tube life is 10,000 hours or more, downside is they are considerably more expensive.
A cheap out of the box chinese machine will often require tons of work before it can be used. Most come with a aluminium honeycomb bed & these are prone to catching fire. A Knife edge bed is easier to clean & safer!
The Co2 Lasers will cut wood & other organic materials such as Acrylic (persex) plywood ,mdf, veneer paper, card. Some plastics such as PVC are an absolute no no as they give of toxic & corrosive fumes. Co2 lasers of these types will not cut metals though can mark it is special coatings are applied.
Our school laser had a 30W tube & could cut 4mm ply or acrylic, any thicker & it struggled. What is the max you want to cut?
If you want to cut or engrave metal you need a fibre laser which is a league above in terms of power & price!
Something that should be remembered is that Laser cutters stink. They produce a lot of smoke & fumes especially if working acrylic & you need decent extraction both for the sake of your lungs & your neighbours. It isnt acceptable to run a pipe out of a ground floor window for example!
They can also be very noisy & the extractors can be as noisy as the machine itself. I recently fitted a decent extraction system for welding & laser to my workshop with silencer etc & when running at full speed its about 50 decibels which is quiet.
Last week i bit the bullet & ordered a new machine from Kent lasers, a Solo desktop. Not cheap but built in the uk & with first class backup.
A lot of people have bought lasers thinking they can make a living from it but the market is probably saturated, if you have a use for it or a niche market you might do well. Im in the position where being recently retired & with a disability it will help me keep building stuff & the laser is a tool to help this.
There is a world of info on you tube, best channel i have found by far is Sarbar multimedia, the guy who runs it is obviously obsessed but has a wealth of good knowledge.