7 1/4 is not massively more expensive than G when you factor in the cost of several large locos, a lot few box cars, track, DCC chips and control units.
Most towns/cities have model engineering clubs or tracks to run at, as well as passenger cars, so really all you need is a loco and a car for the driver to sit on.
We are working on drawings for a NW-2 which would be available as a cow and calf unit, as well as a Dash-9 and SD45.
To clarify a few points from earlier, we use industrial 24v 1hp brushed motors for the drive system, not converted dynamos, 3/8" Reynolds industrial roller chain and taper lock sprockets not bicycle chain, and 180A 24V PWM motor controllers driven by 2 or 4 110aH deep cycle leisure batteries.
All body work is either laser/water jet cut or hand formed out of 2mm, 6mm and 12mm mild steel.