Absynthe, in it's truest form, is illegal in the US. It'll get you drunk as hell the way you can get it, but, for it to be truly hallucinogenic, you ned to have Wormwood in it. Wormwood is what causes the hallucinations, but Absynthe is illegal here.
My friend ordered a tiny flask off of ebay, without Wormwood, and it was $30 for about 8 shots worth.