Hey Blue! welcome to our little sub forum (it appears you have been busy posting elsewhere!) I also appreciate you asking ahead of time about this, as most of the time people come here after they have ordered and got stuck waiting, only to be angry and disappointed. Quick history and then future roll out:
Survive! has had many different business models as they have tried to get their company up and running. As of last spring they decided to do a Kickstarter style funding program. You pay up front the knife you want at a discounted price and in turn they were able to buy finishing equipment/steel etc to get the production runs going in Mass. This means however that there is no guaranteed delivery time. Each style was made in succession in order of popularity and detailed on their production page:
http://surviveknives.com/production-schedule/ The 5.1's are shipping out now to those who pre-ordered them and once all are shipped, the remaining knives will be put up for sale at the regular price. Then come the 4.7's etc etc in order of the list on that link. However due to people being unhappy with the wait times, they are tweaking their regular sales to instead only sell what has been sharpened and finished up in a Monday "sell until they are gone" style on their website. This means you will need to be quick on the draw, or patient, or both.
whew....follow all that?
OK so for the 5.1 or 4.7 you are after, pre-ordering has closed since production started, which means you will need to buy them during one of the Monday offerings. I would suggest signing up for their newsletter and hanging around here/their website for details. Another option is the secondary market, but those are only just now showing up and its a crap shoot as to what will be available.
The reason the wait times are so painful is because they are currently a young growing company. Currently they only have 3 employees and one person does all the sharpening (sharpest production knife you will ever hold). Because of this their are production bottle necks and slow e-mail responses. On top of all of that, everything is new and they are still breaking in the process at the shop, sometimes things break/fail unexpectedly.
If patience is something you can handle, these guys (and gal) are worth the wait and every penny you will spend. I am going to help a buddy shark one of the 5.1's I think once the monday ordering opens.
I know its a lot of info and a bit confusing, but genuinely I appreciate you asking ahead of time and wanted to fill you in! Please feel free to ask any follow ups!
