Good question. Maybe Gary Stern could tell us? Who knows really... he probably has the original BTTF ramp form under his mattress with his giant pile of money!
Seriously though, it seems like you could setup a Kickstarter to ensure at least break even with some money for your time in overhead, offer like 30 ramps @ $225+shipping, this should gross you about $1150 if the Kickstarter is funded and nothing else costs more, if demand is higher, more profit for your time to get them out/shipped/etc.
If the initial batch sell, the $90/ramp cost is still quite reasonable for some profitability to get more out into the market. You could sell to distribution in bulk at like $150, they could retail at $225-$250. That's not unreasonable at all if you ask me, tiny ramps are $50, $75... even $100 all the time. This sucker is huge, and unobtainable. Maybe it would be worth reaching out to Marco/PinballLife/etc and seeing if they want to buy 15 each?
Of course, if it doesn't fund at all, you're just out your time to setup the campaign.