Coleus start so easily from cuttings, speaking for myself I usually just give away cuttings.
Unfortunately, mailing plants has gotten so expensive it's not worthwhile to sell or trade privately. For the cost of shipping you can buy a coleus plant at your local nursery or box store and they usually have a really great selection. Find a friend or neighbor who likes coleus, and if each of you buys a plant then you can trade cuttings and get two different ones for the price of one plant each.
I buy a couple of small starts for my daughter when I visit her in May, usually at Lowe's. She has two large pots that we plant them in on her front porch, and by mid-summer they're huge and beautiful. These are the two I bought her last May. They were 3ft. tall and wide when I visited in October. Gorgeous.
