I use the bottle at midwestsupplies - although I got it from a LHBS. It is plenty for several batches at 28g (not 2g)....
Alternativily, tanin is what you get from Tea, you could steep a few tea bags and put the tea into your skeeter pee. No I have no idea how many
take a look at some mead recomendations (I think usually 1 bag per gallon of must, so for 5 gallons, maybe 5 bags, and that can be made at typical strength, so like 30 oz of hot water with the tea)... - I lied... little idea, not no idea.