You would think that air runes are comparatively cheap since (1) runecrafters can make the highest multiple of OSRS gold air runes over any other rune (increasing quantity of air runes), (2) air running is fairly well-known (again growing supply of air runes), (3) most people would buy an air staff versus a water/fire/earth staff (decreasing demand for air runes). Air runes are 22 gp more expensive than mind/body/fire runs.

Why is it that water (37 gp), and earth runes (39) so much more expensive than fire/mind ranes? Just wondering. There are a few reasons why water runes may be used for blitz/barrage. This is very common in p2p. They aren't uncommon and may only be crafted by very few people.

A lot of monsters drop fire runes in large quantities. Mind runes are largely ineffective. Keep in mind that air runes are used most often in standard spellbook spells. Body runes are cheap since they're almost useless, except for low-cost levelling. Vengeance spells are able to be used 10 at a. using earth runes.

I haven't played in like a year, but from memory, the fastest method to earn money from fighting in F2P is to collect large bones, which can yield perhaps 30k per hour? There aren’t any NPCs of high-level that offer rewards in the form of drops. It is possible to get around 10-15k from less powerful demons. The F2P player will take about 3 hours to buy RuneScape Mobile gold collect 100k combat droplets.