I know a guy who tried the mushroom thing. Had lotsa problems unloading...everyone was like "yeah, gimme"...then he harvested and they sat around. Mind you, he was older than I am (effing old I am) and woulda had a hard time in the concert season selling to kids old enough to be his son/grandson. As others note, seems to be very niche.
You could always try and see. Might work out well. Might not. Never know unless you try.
I wish weed grew like shrooms. Would be awesome. This whole 8-12 wk wait thing is tedious though it does give one a major lesson in patience. Makes me appreciate how hard we humans have to work to survive and thrive. Our relationship with plants is very amazing, incredibly long and complex. I find it very inspiring. I plan on growing a lotta food this summer: 2 garden plots and a community program. I'm growing vertically on trellises. I expect this summer to be a bumper crop: cooler temps, good steady rain. I cannot wait to give my vegetables to local shelters. I believe food is an incredible 'bonding' thing for us humans. Was very hungry this winter (lost weights to give $/life to my plants. Made me realize food is life itself and that if I give it I am not only giving love but life itself.
Sorry, didn't mean to get all mystical on ya, MUST be the mushroom talk!