Anyone know the cheapest place to buy powder paint, in light of the labor day sales?  

You have a PM

Harbor Freight sells a few colors for really cheap. I buy flat black, white, and red from there and it's something like $6 for a pound. 

^ what he said.

 

You can get white, red, yellow and flat-black for around $6 each. Not a great color selection but it is still very cheap.

 

You can also mix them if you have the ability... red+white and you can make a pink etc...