You can find a list of monsters here: http://runescape.wikia.com/wiki/Bestiary - count them if you like.
There is some at falador or "Port Sairiam" where becky is. I think there is some more if you can runecraft some it's very eaisier if you really runecraft. AND IN VARROCK BY THE ANVILS SOUTH FROM...
the only ways to get rune rmor for free is to make it, get it in the party room drops, kill a monster, or clue scrolls for members.
You go to the Rune Shop in Varrock, talk to the wizard, select the Teleport option, and you can mine as much Rune Essence as your inventory can hold.
u can't get it anymore it was a holiday event in 2002