On Mon, 28 Jan 2013 20:01:10 -0500, gfretwell wrote:

I don't know what grades of CO2 are offered, but
I doubt if the grade we were buying would be safe
for consumer use.

If you are buying the CO2 in a Bevco 20 pound bottle, most of these
will end up attached to soda machines and the gas is food safe.
They still consider it a dirty gas compared to medical grade oxygen

Thanks for the warnings - but I'm not the least bit worried about
contaminants in the C02. As gfretwell stated, these tanks are used every
single day in millions of beer kegs and soda dispensing machines.

The problem I'm having is that the C02 and water are only a couple
pennies a liter, but the Soda Stream cola syrup (at $5.00 + 10% tax for a
bottle that makes only 12 liters) is hugely expensive.

Wikipedia lists the "Merchandise 7X" formula for Coca Cola syrup (the
supposed secrecy of which is a carefully orchestrated MARKETING coup),
but almost NONE of the ingredients were easily obtainable at any of my
local grocery stores.

Do you know where I can get these ingredients, at a reasonable price?

http://en.wikipedia.org/wiki/Coca-Cola_formula
Ingredients:
1 oz (28 g) caffeine citrate
3 oz (85 g) citric acid
1 fl oz (30 ml) vanilla extract
1 qt (946 ml) lime juice
2.5 oz (71 g) "flavoring," i.e., "Merchandise 7X"
30 lb (14 kg) sugar
4 fl oz (118.3 ml) cocoa leaf fluid extract --isn't gonna happen
2.5 gal (9.5 l; 2.1 imp gal) water
Plus caramel sufficient to give color

Where the "Flavoring (Merchandise 7X)" is as follows:
1 qrt alcohol
80 oil orange
40 oil cinnamon
120 oil lemon
20 oil coriander
40 oil nutmeg
40 oil neroli