Trident doesn't cost any runes, and you can get more than what you need with RC for single cast spells.
It does seem like a hassle at first, but after a while you'll amass a good amount of runes. Through bossing and various activities etc...
Mage isn't the most imperative thing to an Iron Man here on Alora anyhow. Just range everything until you have enough runes for magic.
I got 99 with fire wave with the bloods i made from 77-99 RC. I killed things like spiritual mages and cyclops for drops. It worked, only took me a few hours to hit 99.