Anyone who looks can find surprising examples of over-graded and under-graded coins in TPG slabs. The trick is to buy under-graded coins for your collection. Buy the coin, not the grade.
http://www.coinweek.com/news/featured-news/the-deal-shopping-mentality-and-rare-coin-prices/ Here is an article I just saw that articulates what I was saying in post 56 better than I did.
I think the better "trick" is to just buy raw coins that would grade MS 65-68 and get them for close to melt value lol.
A Honus Wagner can cost you more than 99.99% of all coins in existence. Don't think ALL baseball cards are valueless, just those made as "collectibles".