I have been drinking absinthe for a long time. I have a few bottles in my liquor cabinet. And I live in the US.  I usually spend about $200 to have two bottles shipped from England. The absinthe I purchase is La Fee, which is considered among the best. It isn't as renowned as Un Emile 68 or Logans Fil, but it's great stuff. 
Absinthe comes in many colors because not all absinthe is made with anis. Bohemian absinthe, also available from La Fee, is blue like Sapphire gin. La Fee's standard offering is a glowing-green product. Other outfits sell yellow, brown, red, and other colors from various makers depending on the herbs and extracts (and food colorings) used. 
To the poster who said it was milky white on that TV show, that is normal and indicative of a good absinthe. That is what happens when you mix water into an anis-based absinthe because anis clouds up with mixed with water. This is called louching. An excellent absinthe is said to produce an excellent "louche" i.e. the proper milky-white hue results. 
It is not "illegal" in the US due to alcohol content; it is solely because of a main ingredient, wormwood, which contains a semi-hallucinogenic compound known as thujon. Thujon has a similar chemical structure to THC, which as you all know is found in pot. The FDA has decided this is too unsafe for us (thank you FDA....) and so they've banned it. Meanwhile, fake absinthe is floating around liquor stores across the country, called "Absente". The key difference is that the Absente contains SOUTHERN wormwood which is thujon-free. Taste the Absente side-by-side with a quality real absinthe and you'll be immediately swayed to the good stuff.