Oh sorry, that is rather vague.
By thing I mean traditional art i.e. the original, done in pen or colored pencil or whatever it is you do. In a medium that will survive some amount of travel, naturally–nice paper or card stock or something.
By mail I mean I want the original in my hands.
By a decent amount I mean I dunno a decent amount.
What I would like the "thing" to actually depict is Applejack with a wicked scar on her stomach, riding on Luna's back.