The good news is that for your 19 acre pond 500 per acre will only cost $7,125 - $10,000. Only double that at 1000/acre. It takes ~1250 PK shrimp to make 1 lb or about $937 per pound at 75 cents.

Swingle experimented with them for growing BG. He stocked ~19.31 lbs to the acre ($17800 - $23750 per acre) along with around 47 lbs of BG (1500/acre). Under fertilization both the shrimp proliferated and the BG grew well. He was able to grow 209 lbs/acre of BG and 94 lbs/acre of PK shrimp in 6 months with this recipe.

Now this is where it gets interesting. He tried this under many scenarios but the highest production of BG he achieved with PK shrimp was ~234 lbs/acre. He achieved this without fertilization and chara and he achieved it with fertilization and brush. Although there was no difference between BG production, the fertilization/brush treatment increased production of PK Shrimp over 6 fold yielding a harvest of 1043 lbs of PK Shrimp per acre. When you think of in terms dollar value that is nearly 1 million dollars per acre.

All kidding aside on how much PK shrimp cost, I saw a much deeper lesson in Swingle's findings. I had always heard they make very good forage. And indeed they grew BG for sure but no better Gambusia. Under a similar treatment (fertilization, no weeds, no brush) using only 1 lb of Gambusia per acre Swingle produced 310 lbs per acre of BG or almost 50% more weight of BG. Swingle also grew BG under fertilization alone. The results were less than with PK shrimp (165 lbs/acre) and so we can say PK shrimp (with fertilization, without plants or brush) can add 26% to the production of BG in 6 months. Gams under the same treatment of fertilization increased production by 88%.

I wonder from time to time why the PK shrimp underperformed the Gams so significantly in Swingle's treatments. It seemed clear that the BG were getting all the PK shrimp they cared to eat. Producing more PK shrimp didn't seemed to help the BG to grow faster. So perhaps, the density of the nutrition is inferior in PK shrimp giving the BG more water to process slowing the rates they could consume prey on a dry matter basis. To be sure, I would focus particularly on cover and habitat for minnow species and focus your investment in species that have better abilities to persist in your pond than fathead minnow. I think these will ultimately go further to invigorate your food chain. This is what I would do in lieu of so many PK shrimp if I were making this choice. If the habitat is good, smaller quantities of PK shrimp will eventually expand to fill the pond so this is in no way meant to discourage trying to establish them.