Steam plants will always cost more than the electric equivalent (although they will also last a lot longer) and if you are starting from scratch then there are a limited number of possibilities.
I have not seen one in the metal, but the Graupner 2 cylinder IST-L plant looks like a useful package and is not too badly priced. Krick also do a suitable plant; The Alex, as do Stuart Models, although the Pintail is expensive by comparison and lastly John Hemmens.
Buying separate engine and boiler is likely to cause you a bit of head scratching, unless you have a local steam enthusiast, simply because in order to put all the relevant 'bits n bobs' together, you really do need some knowledge of what you are buying.
If you have workshop facilities and can machine, then more possibilities open up to you, with engine casting kits.
The alternative is to do what one of the other posters has done and to build up a model, with temporary electric drive and then convert as parts / finance become available.
There are a goodly number of knowledgeable people on the forum, between us I am sure we can get you started in the right direction.
Neil
