Question upgrading my 840-2 with a laser engraver?

Hi,
any suggestions on upgrading my 840-2 as a laser engraver with a laser diode?
We all know Stepcraft has a laser add on for sale, but the internet (bangood and Alie Express) offer a wide variety of lasers, that seems to be mounted on a stepcraft as well...

Although i realy doubt this would work properly, i'm asking all of you if the € 500 Stepcraft Laser is the only right choice to upgrade a stepcraft cnc towards a laser engraver?

good morning, I’m’looking for to upgrade my 420 too with a banggood laser. problem with the stepcraft genuine laser is that it is not powerfull enough for the price. 5000 mw would be a good value. but if you want to cut material properly such 3-5 mm, you have to forget any laser under 10w...