If you order the pure ascorbic acid powder from Puritan.com, you can get the buy 1 get 2 free for $34.90, the 20 oz crystals.
This is 360 teaspoons of 5000 mg doses. <+/- 6 months supply for my scedule of twice per day!>
The cost is between 9 and 10 cents per dose. (34.90/360)
Most ester-c, emergen-c and like products are 1000 mg doses, and even so, are much more expensive.
The baking soda is dirt cheap @ $2.00 per 16 oz and better deals if you buy in bulk from Bob's Red Mill.
so, in short, it's A LOT cheaper to make your own! :)
ALSO, I have heard that if you call Puritan's 800 number and request a catalogue, they give you 75% off on your first order.
Hope this helps for those who have found relief from daily vitmain C ascorbate. I take it upon waking and upon sleeping along with a few other things and it has helped tremendously not just for outbreaks but ALL illness. No colds, no flus, no allergies since I began this regiment. :)