A guy in the US built a MM from all the repro parts that have been remade to date, including getting the lane guides and metal ramps custom made and the wiring loom remade.
Now admittedly this was a one off where he paid retail prices for repro parts, but I think he said it ended up costing him $12,000 all up.
All those little bits and pieces start to add up and unless you are running off a few thousand of those widgets to keep costs down I'm not sure how viable it would be.
