depends:
where u are
who you buy it from <- U WILL get fucked if u r dumb!
quality of weed.
the stuff i got in philly, 20$ bags were like a gram and a lil bit, like 40 per 1/8oz. these were standard prices that the guy sold it but they would always hook me up with more. this was goood weed. the only time anyone had shwag was 15$ for like an eighth
it really depends who you buy it from cause those guys sold it to another guy selling it to different ppl at school and they would pay more for the same stuff!
it really all depends on all of that, cause there were times when there was a decent flow and it was cheep for the same stuff.
also depends on how u smoke it / what you smoke it out of.
if all that is around is semi decent shawg (yea it sucks but still) and smoke it in blunts, you will get stoned. but if you have lots of good weed smoke it out of blunts and you will be fucked the hell up