You can order a single Alien or a 5-pack of all the figures at Entertainment Earth right now! Order the Alien for $14.99 or the 5-pack of Ash, Kane, Dallas, Ripley, and the Alien for $64.99. I got a set... and wouldn't you know it, I've got some quick impressions.
UPDATE 12/20: If you ordered your figures from Super7 at either San Diego Comic-Con or through their web site, you may be receiving them this weekend - mine showed up today. The figures came on blue, unpunched cardbacks and the bonus figure was a clear grey Alien which, as someone who is a little sick of clear figures, I gotta say looked awesome. Check those mailboxes - or order yourself a set! Do it! Send Hasbro a message about how much we love vintage-style figures, people!