MVS carts are basically worthless to the operattors that own them after they stop making them money. That, and the fact that many thousands of the MVS carts were made for most games means that there are a LOT of them out there and a LOT of the people that own them assign very little to no value to them.
In fact, when I bought my MVS cab a couple years ago, the operator threw in about 30 carts with the deal and about 10 or so more were doubles that I sold. To him, they were worthless because they could no longer generate cash flow. To me, they were a treasure.
