Reddit reviews 2W Copper 445nm M140 Blue Diode LD Module W/X-Drive & 405-G-2 Glass Lens

Amazon has a couple of sellers with modules cheaper than pointers....

http://www.amazon.com/dp/B00HFHPPQ0/ref=pe_385040_127541860_TE_3p_dp_1

first google result You'll also have to find a constant current laser diode driver, a module to mount the diode in which has a lens, and a heat sink to put the module on or in.

You can also get ready made modules like this But you would need to get a big heatsink for it. That tiny driver board might overheat as well so this probably isn't the ideal module for engraving. You'll want to end up with something like this. IF you want to make it yourself and need it to run constantly, I'd suggest drilling a hole in a computer CPU heartsink for the module.

You can find a lot more information about how to mount, drive, and assemble these things at LaserPointerForums and PhotonLexicon DIY sections. There is also /r/lasers Some of the message board members run web stores and sell all sorts of useful parts for this sort of thing, often made at home. The guy I used to buy from is closed now though. PhotonLexicon is mostly focused on laser shows, and LPF is more about laser pointers, but between the two you should be able to figure out what you need.

I believe the most common donor projector is a Casio m140, but it's been a long time since I've been messing with lasers and there may be better sources now.