I will have to investigate an automatic trading using the internal market. I know I can place a limit order, but not sure about a market order via the API, but perhaps it is also available.

I was doing all of this manually but it is time consuming and error prone, thus the change to convert. What I have in place now is a auto trades via blocktrades, but they charge about 5% best I can tell. As soon as I get a moment, I'll look at API market orders on the internal market.