Make you a deal - you find a foundry willing to do bronze castings in onesies and twosies for less than $100 a piece, and I will consider it. Is there a plastic Erie-Built in G scale that we can use for patterns?
I always remind potential custom builders - use your equivalent hourly salary as a baseline, and assume nothing custom can be built in less than 100 hours, and you have a ballpark cost. Don't forget overhead and coffee breaks. Usually materials are lost in the noise.