Exodus 27:20 NKJV
"And you shall command the children of Israel that they bring you pure oil of pressed olives for the light, to cause the lamp to burn continually.
It took a lot of resources to make olive oil - 10 lb. of olives for 4 cups of oil. Then you had to use the right utensils to get and collect the oil.
Spiritual parallel: We must be willing to give our time and resources to get what we need. The value we place on the end product will determine what we are willing to give to get it. How do we compare what we give with what we are getting in return? King David was an example of putting value on an offering to God. In 2 Samuel 24:24 he said, "......I will surely buy it from you for a price; nor will I offer burnt offerings to the LORD my God with that which costs me nothing..."
Olives were valuable. The trees and the oil were listed among the things that made the Promised Land so valuable.
Deuteronomy 6:11 NKJV
houses full of all good things, which you did not fill, hewn-out wells which you did not dig, vineyards and olive trees which you did not plant.......
Deuteronomy 8:7-8 NKJV
For the LORD your God is bringing you into a good land, a land of brooks of water, of fountains and springs, that flow out of valleys and hills; a land of wheat and barley, of vines and fig trees and pomegranates, a land of olive oil and honey;
Even the wood from the tree was valuable. See how it was used in the construction of the famous temple built by King Solomon.
1 Kings 6:23,31-33 NKJV
[23] Inside the inner sanctuary he made two cherubim of olive wood, each ten cubits high.
[31] For the entrance of the inner sanctuary he made doors of olive wood; the lintel and doorposts were one-fifth of the wall. [32] The two doors were of olive wood; and he carved on them figures of cherubim, palm trees, and open flowers, and overlaid them with gold; and he spread gold on the cherubim and on the palm trees. [33] So for the door of the sanctuary he also made doorposts of olive wood, one-fourth of the wall.
The olive tree and the oil from it are mentioned a number of other times in the scripture, each time revealing the value of this tree and its products.