This is the reason why saffron is so expensive!

With even the most inexpensive quality of saffron costing more than your Starbucks latte, it’s safe to say saffron is expensive, a luxury if you most. It is often touted as the most expensive spice in the world, and rightfully so. But because of its immense value, saffron is often adulterated by the addition of substances such as pollen from other flowers. In order to understand how saffron threads are adulterated, it is important to understand the process behind procuring them.
Saffron is harvested from the flower of the saffron crocus (crocus sativus) which blooms only in autumn. It is after skilled pickers harvest 150,000 to 200,000 flowers by hand, you can collect 60 to 80 grams of saffron.
To make things more difficult, the saffron crocus is a triploid hybrid species, which means it’s sterile and cannot be bred. Although it has been cultivated for more than 3,500 years, all plants cultivated worldwide originate only from daughter bulbs. For almost 100 years, there has been controversy as to the possible parent species of the saffron crocus are. If the parent species were known, changes could be inserted into the crocus genome by new breeding.
But recent studies may have solved this mystery. "We have managed to understand the origins of the saffron crocus and shed light on the parent species using molecular and cytogenetic methods," says Thomas Schmidt, Professor of Plant Cell and Molecular Biology at TU Dresden's Institute of Botany.
So here’s what we finally know – the saffron crocus is descended from only one species – the wild species Crocus cartwrightianus which is found in Greece.

Even after we know the source of saffron, it's procuring process still remains incredibly taxing and difficult, which is why the spice remains extremely expensive.