FYI: If you own a Region 1 DVD player, or multi-region DVD player, the Criterion Collection has "For All Mankind" available on DVD.
More information on the Criterion Collection set can be found here: http://www.criterion.com/films/599It's also available on Blu-Ray.
I would recommend it, since Criterion is famous for literally going all out in maintaining the highest picture and sound quality for their releases. Because of this, their films come with a premium price, but it's well worth it if you are a fan.