Even lunar space elevator will cost an insane amount of money (and likely still not possible in this century), and it will be irrational to build it just to get some cheap fuel into orbit.

And even then gas station in Lunar orbit is useless. If there is a need to refuel, you will simply get fuel into orbit directly from whatever container in the elevator to the ship nearby. There is zero point in inserting a proxy station in the middle of this process.

However we juggle the possibilities of space travel, in 99% of all schemes gas station in space is useless.