I bought a 6 month supply on ebay and paid roughly $45.
I bought the 22lb and less one and just use half an application tube on my tyke, then saran wrap, ziplock, then refrigerate the other portion.
The guy I ordered from was in Australia, but I double checked his feedback as well as the active ingredients and it's the exact same as the US formulation.
So far it's worked great for me!
Charlotte