I’m not claiming it’s reliable; that’s just the number I found. For that matter, I haven’t seen the list myself, so I can’t even verify that it’s accurately reported as the DEA’s number.
It’s definitely not an offer. 
28,846 plants.
I had a friend in college who used to grow plants on his farm for personal use. He would always weigh what he harvested from the plant after it was dried and clipped, so he could know just how much money he was saving by not having to buy anything. He usually got around 2-3 ounces from a plant, of top grade quality. So approx. 1000$ per plant, street value could be expected I imagine.
For what it’s worth, I heard on the radio that they busted a grow house in my area and found 129 plants estimated to be worth about $190,000. Being on the conservative side, I decided that if I ever found a pot plant on the side of the road, I could probably sell it for $1000.