Nissa Revane - Zendikar $13.62
Nissa’s steady growth isn’t surprising considering that Elves have gotten tons of support recently. She’s moved about a dollar on average over the past month, so it’s possible she hasn’t hit her ceiling quite yet. $15 is very reasonable for this Elf-happy walker.
Beacon of Immortality - Fifth Dawn $5.42
Brought up a lot recently for its combo with the Magic Origins enchantment Tainted Remedy, Beacon of Immortality has been hovering around $5 for a long time. Doubling your life total is good, and targeting another player with Tainted Remedy on the board means they simply die. I don’t see this blowing up in price, but I think it’s a solid buy if you need it for a deck.
Lightning Greaves - Mirrodin $6.65
Greaves are a Commander staple and the original printing has finally surpassed the other non-foil printings. This is just a card that will always be worth something and $6 is a fair price for this solid equipment.
Grim Monolith - Urza's Legacy $28.42
On the Reserved list, Grim Monolith is just showing its steady organic growth as Eternal and Commander players slowly continue to dwindle the supply. If you need one, it’s not dropping at any point.
Master of the Pearl Trident - Magic 2013 (M13) $5.97
A Merfolk staple, you should probably already have your playset at this point if you’re planning on playing the deck. The functional reprint of the ancient Lord of Atlantis, who’s a $5 card even with all of its reprintings, the Master has only one printing. Barring a reprint, seeing this as a $10 card come Modern season isn’t out of the realm of possibility.
Academy Ruins - Modern Masters $12.99
Modern playable and a staple in Commander blue decks, Academy Ruins are a $13 card and probably will continue to grow organically over time.
Grim Haruspex - Ugin's Fate Promos $8.14
It’s interesting that this is the version of Grim Haruspex showing all the growth. It’s a staple in Standard Abzan Collected Company decks. This is a decent creature to draw you a card or two. The original version is still roughly a bulk rare, as this promo version climbs towards $10. I’d invest in the original set versions as the Ugin’s Fate promos dry up, and who really wants to pay $8-10 for this guy when you can get a set foil for $1.50?
Lord of Atlantis - Timeshifted $9.10
The only black-bordered Lord of Atlantis that isn’t Alpha or Beta, this should be $10 pretty soon. It’s probably the best version of the original Merfolk lord to invest in.
Mindslaver - Mirrodin $5.12
The fact this is only $5 is somewhat surprising considering how broken a card it is. It’s a Modern-playable win condition. I don’t see a major spike coming too soon, but if in the next Modern season a deck with Mindslaver wins big, the days of this hated artifact staying this low will be over.
Glimmervoid - Modern Masters $23.71
An awesome mana-fixer for artifact decks, Glimmervoid has already doubled in price since late May 2015. I think this being a $25 land is reasonable. Since it’s desired as a four-of, there’s still more room for it to grow.
Greater Auramancy - Shadowmoor $13.48
Enchantment-based decks are going nuts with the printing of Starfield of Nyx and the reprinting of Sigil of the Empty Throne - plus other cool Enchantments and support being printed all of the time these days. Giving all of your Enchantments shroud plus your Enchanted creatures shroud is a powerful effect. Barring a reprint, this is a solid investment. It could be in the next Modern Masters, but that won’t be until 2017, and it’s doubtful that this will be in a supplemental product.
Trinisphere - Darksteel $6.01
A hoser for combo decks in Legacy, this is simply organic growth for a solid sideboard card. You don’t see it played in Modern, though. If it ever did, you’d see this being a $10 card. It probably will get there eventually anyway.
Platinum Angel - Mirrodin $8.25
The growth of the popular artifact Angel may be hampered only somewhat by its From the Vault: Angels printing. Having a printing in M10, M11, and Tenth Edition sort of limits the growth potential of this guy. But being a $10 card eventually isn’t out of the question at all.
Swarmyard - Time Spiral $8.51
A bit of a niche land, it sees play in Commander. Its solid growth is real, so if you want one, why not get one? It regenerates Insects, Rats, Spiders, or Squirrels. Rat tribal is a thing, you know.
The only card that screams out to me as being overpriced is Grim Haruspex’s Ugin’s Fate promo and all that does is tell me that the other printings are extremely underpriced. The others are all solid holds, except for Master of the Pearl Trident which is probably a buy.