Well...you know stationary shops? Find pens. Try em out till you find the one you want/like :)
Don't be worried about trying out stuff, even if you don't get what you're looking for first time, it'll still be worth it and interesting, like fr0st sez
peas
oh! ps. potato prints: get big potato, cut in half, carve design into surface, let it dry a bit, ink/paint it up and away you go