Hello,
I got to coalfired 5 Inch ones but to give you Food for thought you might be able to get the CASPER Locomotive made by Modelbow Atelier Apeldoorn in the netherlands . Saw the engine and find it well made and relatively low priced . To get a 3,5 Inch one is another idea but I read from your post that your aim might be a coalfired gauge 1 one. There are a few other reasonable ideas but they are even more expensive .
cheers Joe