Yeah, under 5mW is legal in the states so that makes sense.
An IR diode needs ~2V so the driver isn't supplying 12V. That would bake the diode instantly ^_^
You can get overspec green modules at o-like or you can get underspec green modules a lot cheaper from deal extreme.
$/mW you are likely better off with DX but if you want a decent quality module, O-Like is of course better.
You would pretty much need a laser power meter to "pot mod" your green
as it is up to 30mW accurately and that is only if there is a potentiometer available for you to play with.
They might have turned down the output and just stuck a 5mW on there because they were cheap too.
It is a little complicated I'd recommend leaving it as a working laser and doing a bit of research on "ddl drivers", "dummy loads", and then build your own lab style laser at the output you want with a better module.
That way you will still have your existing laser to play with, as well as a powerful green that you did yourself.
The sense of accomplishment you get by powering up your first laser is addictive though. You might end up spending more and more on this hobby as you learn new things
