Unless there are widespread helium-3 fusion reactors, the demand for it is about $2000/liter for mostly scientific and imaging purposes. Even then it’s a sort of a niche driven price since when the US was willing to bother decaying tritium for it it was like $100 a liter.

Making a helium-3 fusion reactor is a tougher problem than mining on the moon. And even then making helium-3 on earth is cheaper than going to the moon to mine it.

Mining the moon for Helium-3 would be something someone would do once a colony is established, not a reason to establish one.

Probably the most lucrative thing to mine on the moon is water.

Moon-mined Helium 3 is currently a non-solution in search of a problem.