If you couldn't sell it on then, no, it's not good value for money but given that pins seem to be generally holding their value currently then the price is almost irrelevent so long as you can afford the money up front. It could be $100k and if that was the accepted market price then they would still regularly change hands for that money between the select few people that have that kind of spare money to move around. Pinball is a hobby where many collectors sell as often as they buy so the prices don't necessarily represent their actual value.

The price games fetch is not just based on how good they are. See CC and BBB for examples. MM happens to be rare AND a great game so it's quite sought after.

Ultimately, no one can know for sure why certain games fetch the prices they do. It's an organic process that is affected by many things. But rarity and popularity are two of the major factors.

That's the way I see it anyway.