Air runes seem to be relatively inexpensive since (1) runecrafters are able to OSRS gold create the highest multiple of any runes (increasing supply), (2) airrunning is extremely popular (again increasing quantity of airrunes), and (3) most people would prefer an air staff over earth, water, or fire staff (decreasing requirement for airrunes). However, air runes (22 grams) are higher priced than fire/mind/body runes.
Why is earth runes and water (37 grams each) more expensive than fire or mind runes? I'm just curious. There are a variety of motives. Runes of water are a popular choice for barrage and blitz. They are scarce and hard to make.
Fire runes are often dropped by a variety of monsters. Mind runes can be quite ineffective. Keep in mind that air runs are the runes that are most frequently seen in spells that are standard in the spelling book. Body runes can be very cheap because they are practically unusable except for cheap levels. The Vengeance spell uses 10 earth runes at any given time. This spell isn't P2P.
I haven’t played in around a decade, however I do recall the most efficient method to buy RuneScape Mobile gold earn money from fighting in F2P is to gather large bones. This can give you 30k an hr. There aren't really any high-level NPCs you can kill that offer rewarding rewards. It is possible to get around 10-15k from less powerful demons. F2P players will require about 3 hours to earn 100k from combat drops.
