I'm an freelance translator and I'd like to warn you about the most serious pitfall of crowdsourcing - the quality. I've seen Facebook translation onto my language (Polish) and it's terrible. There are other projects done this way and most of them are of extremely poor quality.
Problem is - if you want quality content, you need professionals do the job. They don't necessarily have to be paid professionals (translators) - maybe just the people from your field, who wish to contribute for some reason or other. But in crowdsourcing you have to take into account a lot of poor translations and you have to introduce some form of quality control - best would be to hire editors, but maybe some kind of voting system would do.
Just don't let your content be translated without QA, because you won't sell much of it.

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