I'll try to break down a hand poured Senko's price for you. Let's assume you bought a 5 gallon bucket of plastol for $125 shipped ($25/Gallon). You also bought a gallon of Salt for $4, and a gallon of softener for $30. Let's also say you use the normal senko formula of 4 oz. plastic - 2 oz. Salt - 1 oz Softener.
You can roughly make a little over 400 senkos per gallon of plastic. So we'll say you only used one gallon of your original 5 gallon bucket in this scenerio.
Gallon of Plastic - $25
1/2 Gallon of Salt - $2
1 Quart of Softener - $7.50
we'll say 4 oz. of Colorant - $6
and we'll guess 4 oz. of Glitter - $6
That's a total of $46.50. So we'll divide $46.50 by the 400 sticks that you made, which equals a total of $.12 per stick!
You costs greatly go down based on how much material you buy, especially plastol. Most of the time a gallon of plastol alone costs $40, plus shipping. But you can buy a 5 gallon bucket of plastic for $100, plus usually $25 shipping. So that's $40 a gallon vs. $25 a gallon, which is a huge difference really.