The miracle of Chanukah that we commemorate was that the oil burned for 8 days, until they were able to replenish it. Why did it take 8 days to make new oil for the menorah? The normal process for making oil doesn't take that long. Furthermore the talmud (peah) discusses olive trees who's produce is so full that oil literally leaks out. Couldn't they have accessed usable oil more quickly?
There are two explanations provided for the eight day delay in getting new ritually pure oil.
One opinion is that the oil was produced in a region that was a four day journey from Jerusalem. This is the explanation of the Ran on Shabbos 21b. The Meiri identifies the oil producing region as Tekoa.
The other opinion is that the delay was because they were all in a state of tumas meis - ritual impurity resulting from contact with a dead body, and it takes seven days to be purified from such tumah. Only after they were tahor - ritually pure - would they be able to produce ritually pure oil. (See Beis Yosef OC 670)
The main thing that is bothering the person asking the question is why the oil could not have been made more quickly and more locally.
The answer is that true, there probably were viable alternatives to having to wait eight days, and since they of course did not know that the one flask of oil would miraculously last for eight days, they probably expected to avail themselves of one of these alternatives after one day. Nevertheless, they were obligated to immediately restore normal production of pure oil taken from where they normally got the most choice oil, which took eight days for the reasons mentioned in the previous answer.
Thus the miracle of the oil of Chanukah was that they did not have to resort to a second best lighting of the menorah because the oil miraculously burned long enough until the production of the best oil was restored.