One more piece of advice:
If your players like the game, they are most likely willing to help!!
I've had great experiences with crowd sourcing for an app project (not a game). What we did there was checking for the device's language and when it wasn't one we already supported showed a button saying "Translate for free updates". This then lead to a page where we listed all strings in the app, a textfield beside each one and a submit button (which simply sent the result to our servers).
Worked fantastic and is now translated into 26 languages.
Just be aware of trolls and check the translations for swear words...