I am picking up lesser grade Mantle cards that I want now, because the inflation will seep down the grade spectrum like it has with the 1952 Mantle and to some extent the 1954 Aaron, and I am afraid I will be paying a lot more if I wait. I am already too late to pick up a 1952 Mantle on budget and I had to settle for an Aaron RC that is nice for the grade but a bit below where I'd have liked to be. I could buy a 52T or 51B if I wanted to liquidate a big chunk of my collection but I don't want to do that. Plus, I am getting the cards that look like the ones I had when I was a kid. I bought one of these in about this shape for $3.25 at a card club auction around 1978. Cost me a bit more this time.
This one is actually an upgrade from the one I had as kid but again, the one I had in 1978 cost me $2:
As for undervalued, my suggestion:
