The Railmaster is such a classic. It took me two years to find one and I don't think I'll ever let mine go.
*If* you can find one, they seem to go for around £1600-£1900, depending on condition and accessories.
As for dimensions, these use the same case as the Aqua Terra of the same era, so any numbers you find for that model will apply. I don't have the measurements handy right now, but it wears very thin in my experience.
Mine says hello: