We plan to add a fourth locomotive to Eskalon in the next month or two. Its most likely going to be D10, a Liliput model of a Zillertalbahn shunter. It will fit in well with the layout.
However we've also got our eyes on a Roco shunter too. This may follow later in the year or early next year to help supplement Plymouth on mine work. One problem with HOe is that you arn't inundated with choice with regards to rolling stock. Still this makes the choice of what to get easier and saves money!