Oddley, I know what you mean, I understand the point - BUT - in terms of gettlng started, its not actually essential.
In the USA there is a requirement to use ascorbate + nitrIte for bacon for sale. Using saltpetre (as shanew intends) is forbidden in bacon for sale. Over there.
Here in Europe however, saltpetre is permitted for bacon (though very little used commercially), and ascorbate is not legally required.
For example ascorbate is *not* used in curing Prince Charles' bacon
http://www.duchyoriginals.com/meat_bacon_organic.htmResidual nitrite (minimised by ascorbate) does produce nitrosamines on frying. Nitrosamines are harmful according to test tube work. However, since they are formed in the gut (for example after eating spinach) it has never been shown that bacon made according to the american law is actually any healthier in practice. It could well be. However, I don't know of any epidemiological evidence that eating bacon cured without ascorbate is actually harmful. For my reading, ascorbate is a useful, harmless, refinement - but not truly essential.
Sodium ascorbate is approved as E301, the calcium version is E302 and the potassium salt E303. Other than minor and non-critical adjustments to the ideal quantity, they could be interchanged. Vitamin C itself (Ascorbic acid, E300) is not advised for curing.
I'm not sure that Ascorbate is helpful when using nitrAte (saltpetre), as Shanew seemingly intends.
My advice was (and remains) to start with a commercial ready-mix cure - which would almost certainly be based on nitrIte (rather than saltpetre), and would contain ascorbate - because it accelerates nitrIte curing, quite apart from any health benefits.
But for DIY, all that's really essential in the way of strange ingredients is a little saltpetre.