The amount of hydroxyl on the lunar surface is considerable, roughly 10 million tonnes at any instant, and much more over the Moon’s history. OH/H2O inside the Moon is also huge, estimated as 40 trillion to quadrillions of tonnes; with presumably only a small fraction ever reaching the PSRs (where about one billion tonnes reside). A reasonable estimate of water ever delivered to the lunar surface by comets and asteroids is 0.1–6 trillion tonnes, with perhaps 10–100 billion tonnes not lost to ionization on impact.
Moon Express plans to create a robotic lunar hydroxyl mining machine. It will fill a small fuel tank then it will launch into lunar orbit.
A second lunar robot lander will use the lunar orbit fuel to lower the cost.
Then there will two robotic lunar lander-miners
This will continue to four then eight lunar landers and a large lunar orbit fuel depot.
Then when the setup is large enough a lunar fuel depot will be towed to low earth orbit where it will be a low earth or other earth orbit fuel depot where it can sold to other companies and missions.
The cost of space exploration would then approach the cost of launching to earth orbit.
SOURCES- Arxiv, moon express