you can find wild ones, but they're rare. they're left by people who bought them.also yes, the only legal way to obtain one is by buying one.once in a blue moon you'll find one unowned in the wilderness.
unless you download that mod that finds them...
It isn't a mod. It's a script. A mod is a modification, not an exploitation. Scripts merely exploit the code already there, you can only use mods if you're server host.
When will you and your legion of idiots get banned already?
You can take the horse of someone else if they are not currently online (which is extremely likely). Otherwise, get one from the shop. I normally end up finding them somewhere after a player leaves, like near the stable or wilderness near Port Town.
What stable?
Holy crap, I forgot... I think there was, or still is, a stable for leaving horses... I vaguely, VAGUELY remember it... Now I'm sad because that's all I remember.
There hasn't ever been one.