"Again - the ad was from the link you provided - i
Post# of 43064
There are currently 90 listings on the link I provided. The ad from the link you used showing $0.28/lb is a bit lower than even what other people are generally willing to pay on the same site...but from what I can see that particular seller currently only has 40,000 lbs (20 tons) available, the plastic has to be picked up from Ohio, and since they test for "leakers" it means there may be milk residue in them.
I'm just saying that if you see an ad offering to sell plastic at a price generally out of line with the other ads, there may be something which makes it less valuable.
"I couldn't have been clearer - the seller/buyer of waste HDPE would simply keep the fuel they made, which would reduce the amount of fuel they normally buy for their operations by the same amount, saving them the cost of buying that fuel at retail prices."
Well, if the buyer of a processor currently generates 40 tons/day of plastic to run a processor, that processor is actually able to turn that plastic into 75% diesel and that organization uses 7,500 gallons of diesel per day while still paying the full retail price of $3.73/gallon for diesel, then they can keep a processor at full production and save paying $3.73/gallon to buy diesel from another party. That would turn the $0.28/lb from the ad or $560/ton HDPE into $699/ton instead of $506/ton at the diesel spot price. Based on your assumptions, you're correct.