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35 is pretty high, seeing as they cost nearly nothing to grow (which i suggest doing, especially for your first trip)
afoaf just went to coachella and bought a couple eighths of mushrooms for $20 a peice and brought them back with him on the plane and then sold them for $70 a peice to rich kids in a neighboring suburb who didn't know any better.
you can take half and eighth and get really "high" from them, but you won't really get anything that constitutes a trip unless they're supremely potent.
but i wouldn't pay anything more than $30 for them, and only then if they were VERY hard to come by and there was NO way you could grow your own. they really should only cost $5-15 for an eighth.