If you have 20k in cash and want to invest in one post-war card...

[FrankWakefield]

If....
Then I'd hope I talk myself out of it.

Don't invest in baseball cards. Recognize it's a hobby... a piece of cardboard, a bookmark. Buy a card for some intrinsic value: who it depicts, the history of the set it's in, how it was printed, the year of the card as it's tied with something the player or his team accomplished that year... but recognize that it's not an investment.

Here are investments...

An education
A home
Mutual funds
gold or silver bullion (not coin collecting)
Stocks, if you're gonna pay attention to the market, the company...
Bonds

If you're in your 20's and have that 20k to invest, I suggest this investment. Drive out into the country and find 5 acres to buy (this won't work in desert areas, some mountainous areas, so this terrain might not be available). Buy five acres, then plant a bunch of hardwood saplings. Walnut, Cherry, some kind of hardwood trees. Get an agricultural extension agent to get you information and advice. You'll have to go tend them the first year or two; maybe water them or protect them from rabbits or deer. After a few years you can leave them to their own, they'll grow. Wait 30 to 40 years (this is why you need to me a young investor). Then hire someone to harvest the trees and get them to a mill or market. This investment will yield money enough for retirement, putting grandkids through college and/or helping with a down payment on a home... and you still have the 5 acres that you could either sell or convince a grandkid to plant some hardwood saplings.

I'm all about collecting old ball cards. It just bothers me when I hear someone "needs" a certain card. I say it sometimes. I don't need the card, maybe I want it. When I hear a sorority girl say that she invested in some Guess jeans, or a guy investing in a motorcycle, or someone investing in a pontoon boat... or such. Those aren't investments. An investment is something that you and others recognize will grow in value for which there will remain a ready market. You have to live somewhere, so a home is a necessity, it's a special form of investment. An education is special, to... it doesn't mean you'll make more money, it does increase employment opportunities. The rest of the investments need to be something you're willing to part with. You could sell stocks, bonds, mutual funds. A certificate of deposit could be cashed in... do you really wanna be selling baseball cards as you would a few shares of stock? No, you'll be attached to the cards.

Invest in investments, not hobbies.