There are costs involved over and above the price of a small locomotive such as that which you are looking for. Primary amongst these is moving the loco to where you want it to wind up, assuming you don't find one near-by. Even if handled only a few ...
A traditional diesel electric locomotive for passenger service will cost about $2M. Electrics seem to be going for more, though I don't know why. Seems to me they should be less. Transformers are cheaper than diesel engines. The Acela, JetTrain, ICE ...
go to the block line.com go to the American Association of Private Railroad Coach owners. Go to the prr fan club this is an easy one.