Six different billboard wood-era reefer sides printed on 12 cardstock sides full color, a pair of each. Make your own boxcars from scratch, use the pairs of printed sides with an old kit, or glue them to the sides of an existing boxcar.
That's less than $1 per pair of sides! This would fit right in with any steam or early diesel-era layout.
Note: shipping is about the same rate for US, Canada and world-wide