It's certainly cheap, considering a 2.5W laser module with a power supply runs around USD150. And the loads involved mean that it doesn't take much at all to move that laser around with a reasonable degree of precision - looks like it uses a similar roller and belt setup to my 3D printer which will happily repeat to within 0.05mm (about 0.002").
Depends what you want to do with it. Is it big enough for what you want, and has it got the guts to cut / engrave what you want? These little blue lasers (I have a 3.5W version of the laser fitted to my router), will cut fabric and very thin wood and will mark wood / some plastic but won't touch most metals.
If you're not looking to cut 1/4" plywood or mark raw aluminium (black anodised comes up ok) and it's the right size, at this price it's probably not too big a gamble.
I've fitted a module to my CNC, Milton. It's a PITA.
You need a driver board/power supply for them that supports PWM power control. Not usually supplied, they seem to default to a simpler/cheaper "on/off" version which can't handle being chopped at any kind of usually frequency. Then you need to find a PWM output on your BOB - perhaps for the spindle control, with a separate pair of enable outputs to select between the spindle and the laser. Then you need your control software to be able to set the rate and select the output. I did it in Mach3 with some macros to override M3, M5 and M101 (for laser on) using the spindle speed S parameter to set the power output.
I use bobcad software and played with it last night, If I set the bit size to .0001 I think I can use Bob Cad for my G code. It works on the simulator.
My thought was to put a switch on my Z axis to cut the laser on and off it might work. ?????
Just will not be able to control the out put in the laser, Will just have to use the speed to do that.