I would not buy a laser off Aliexpress. The offerings there are a cesspool of bait and switch and outright lies with respect to any power numbers. I would recommend purchasing directly from the manufacturer, and I would stick to this list of companies:
- XTool
- Atomstack
- Ortur
- Sculpfun
- NEJE
These companies also lie about power, but you will find demonstration and comparison videos on YouTube for many of the laser modules from these companies. Personally, I purchased the NEJE A40640 and am reasonably happy with it. I’ve done a lot of cutting with it, and lately done a substantial amount of engraving on tiles. As for bang for the buck, I’d look at the NEJE A40630 module. Don’t expect K40 performance from a diode laser.
Several of the companies above are offering 20W, quad beam laser modules this year. Performance is impressive, but so is the price at around $450 to $500.