That L-Cheapo laser looks OK but they don’t give any photos or documentation on their driver. You can make you own with some work. 2.1W 445nm Laser diodes, lenses, heat sinks, drivers and safety goggles can be found on Ebay.
I’m just going to dump a comment that I made on Thingiverse below in case it is useful for someone starting to work on this mod:
I think that one small change needs to be made in the Marlin firmware to get a PWM TTL signal out to control the laser. The RAMPS’s unused printer fan PWM output pin is used to control the On/Off state and intensity of the laser though the laser’s “TTL” input. The default for the fan pin is a transistor driving 12V between connector P3 and P4. This needs to be switched in the firmware to a TTL output like D4 on the SERVO 4 connector. Changing the motherboard #define in the Configuration.h file to this should remap the fan output to the SERVO 4 connector:
“#define MOTHERBOARD BOARD_RAMPS_13_EEB”
Note that I have not tried this yet. Others please chime in if other changes are needed or I messed this up.
That was on the firmware side. Some work must be also done on the gcode generation. To control the fan output pin the gcode command “M106 PWMvalue” needs to be inserted into your gcode by a post processor. Forum user ductsoup is working on a Python script to do this post processing on Inkscape generated gcode (http://www.vicious1.com/forums/topic/laser-gcode/).