There's been SO many discussions on just this topic and its many variations!
Playing cards are NOT a good investment. Period.
Remember all those people who thought they'd put their kids through college by buying "Death of Superman #1" in the black-bag edition? There were so many made, comic book stores use them to fill drafty gaps in the walls or shred them to use as packing filler - they can hardly give them away, they're selling for so little now. Maybe after several hundred thousand of them have become landfill under a municipal building somewhere will then even start to come back to the original retail value, never mind higher. Those kids are goin' to community college!
There are many factors beyond simple rarity that affect the price of a deck of cards. The original "Holy Grail" of card collectors was the Black Ghost by Ellusionist - not the current, second edition but the originals. At first they weren't even a customer premium - they were handed out to selected celebrities in the magic community and friends of the company and such. Demand peaked at around $400 a pack on eBay. And that was a print run of 5,000 - considered rare at the time because that was the smallest run USPC would make and companies like Expert and Legends didn't exist yet. The price eventually eroded to the point where they were going for maybe $50 a pack, sometimes even less. It's only since Ellusionist gave away the last of the supply that the price has started to bounce back a little.
Meanwhile, another 5,000-printed deck, the Bicycle New Fan Back Gold Seal Edition in black, still sells for between $5 and $10. And the super-rare white version, only 1,000 made, never commanded the price that the Black Ghost did.
Demand and supply, supply and demand. Plain and simple. Your deck might be one of only 1,000 or 500 made, but if only 100 or 200 people are actively seeking it out and interested in owning it, well, pricing is going to be a little soft. Meanwhile, decks like the color editions of the Smoke and Mirrors decks were made in the low five figures but they sell for a noteworthy price because so many people want them.
Demand and supply both have a randomizing factor - time. For supply, that number only decreases over time as decks are lost, destroyed, sold out, etc. Supply can be fickle. There's always a spike in price for a limited edition deck when it first comes out, but once the feeding frenzy dies down, the demand gets weaker and the supply is enough to meet it - or at least enough to meet the demand of those who can afford it at the current market.price.
Funny things happen in the marketplace - it's not usually the intentionally rare decks that become worth something, but the ones never meant to be rare which end up by uncontrollable circumstances becoming rare. These are usually the vintage decks. The biggest example are the War Series. USPC released a series of four decks, one for each branch of the military, way back in early 1918 as a way to support the war effort by getting people together to play cards (a cheap entertainment requiring few resources) and to raise money for war bonds. The decks were Big Gun (Army), Dreadnaught (Navy), Flying Aces (Army Air Corps, predecessor to the Air Force) and Invincible (Marine Corps). They were not meant to be limited editions, not sold as collectibles, etc. - but the full set in mint, still-sealed condition could buy you a late-model used economy car. When the Great War, now known as World War I, ended, the decks were pulled from production and demand for them dropped - I wouldn't be surprised if many if not most of the decks were returned to USPC by retailers as unsold goods. They are possibly the decks with the shortest production runs of any of the Bicycle backs in the "Mrs. Robinson" book of the classic, vintage backs.
...and they were NEVER meant to be collectibles.
"Investing" in any of the modern, rare, "collectible" decks, especially with the intent to sell them any time within a generation from when you bought them, is a lot like buying cheapo penny stocks in bulk on the hopes that the price will rise a few cents and you can "make a killing" in the marketplace. Craps might be a better option, or perhaps a slot machine. A smart stock owner will buy stocks today for selling perhaps 30, 40, 50 years or more down the road, since the stock market's general tendency trends upward over long periods of time. You diversify so you don't have all your investments in any one company or industry, and you buy reputable stocks to invest in reputable companies. If you're younger, you toss in just a reasonable amount of risk, if the potential payoff is worth the chance; as you age, you progressively minimize your risk as you get closer and closer to the time you want to use that money for something else - a retirement, a house, a college education, a trip around the world, what have you.
Buy what playing cards you want because you love them, not because you think they're a good investment. There are no "blue chip" decks out there, meant to be solid investment material for the long haul.