Depends on the condition of the board, frankly. There is no "overpaid" or "underpaid" without actually looking at the board. That said, $60 is eminently reasonable for an M2 in fair to good cosmetic with no functional problems. (Bear in mind, prices are also on the rise for all buckling spring boards. M2 included.)
If the capacitors are leaky, my general recommendation is to repair ASAP, as the chemicals can damage the PCB and potentially the matrix over time. Otherwise, there's not many real problems with the M2.
There's nothing actually wrong with the M2 either. People don't like it - but that's strictly personal preference. I'm not a huge fan, but it's still a solid keyboard.
So depending on condition, I'd say you probably got either a fair price or a very good deal.