Liquidex is the liquid form of Arimidex. They are both the chemical anastrozole. Arimidex is the pill form. As far as legal sites go, keep searching I've seen them posted numerous times.
As far as estrogen blocking is concerned, Anastrozole will help reduce circulatory estrogen and should be run about a week before the cycle and throughout the cycle until end of clomid therapy. Nolvadex is used only if gyno symptoms occur in which case you'd take it at 40-60mg/ED. Nolvadex does not reduce circulatory estrogen levels but rather binds to the mammary gland thus not allowing estrogen to bind and cause gyno.
Some say you can obtain a 90 day legal supply. Others disagree. I've personally ordered from an online drug store before I found a "real" source and it came through fine.