Micro photograph of marijuana THC glands. As of 2015 cannabis industry prices of marijuana strains can fluctuate daily from $5 to $20 per dry gram. An average dry ounce will cost $150 to $225. Because of the concentrated percentage of THC in marijuana extracts they hover in price around $30 to $70 per gram. Marijuana seeds can fluctuate in worth from $1 to $10 per seed and up depending on the vendor per order selections from 1 to 5 to 10 seeds.