There are a lot of popular EDH (Commander) cards in the Theros sets, and Archetype of Courage is one of them. Giving all of your creatures first strike is cool, but denying your opponents’ creatures from having it is even better.
Archetype of Courage has become a very popular card in aggressive Commander decks such as Anafenza, Kin-Tree Spirit, Odric, Master Tactician, and Kytheon, Hero of Akros, among others. They buylist for about a nickel (0.05 USD) and foils tend to list much higher, around a quarter (0.25 USD). So there is a little cash to be had digging up extra copies of this Archetype.
Like, Archetype of Courage, Archetype of Imagination is a popular Commander card. It’s for a much different reason, however. The regular non-foil printings are about 0.05 - 0.10 USD on buylists, rivalling Courage. But foils buylist for as much as 1.25 USD. It turns out making your creatures gain flying and make all others lose it is a lot better. The Commanders who take advantage of this Archetype most include Aboshan, Cephalid Emperor, Tibor and Lumia, and Tromokratis, among many others.
This functional reprint of Oblivion Ring is, guess what, popular in Commander. Overall, it’s just a good card, though. Casual players run it, too. The non-foil versions will probably never be worth a ton of money, especially as there was a reprint in Commander 2015. They can buylist for only a nickel (0.05 USD).
However, the foils are where the money is for this card, much like the Archetypes. Foil copies buylist for about 0.75 USD, but can be found on some lists for as high as 1.50 USD or more!
Like Bile Blight, Dissolve was a pretty good card during its time in Standard. The Scry 1 made it strictly better than most 3 mana counterspell. Now, it mostly just sees Commander play. You can still get a dime for these, and a quarter for foils - including the FNM promo. So if you have a bunch of these around, be sure not to just throw them in a bulk box.
Minotaurs were made very popular by a number of cards from Theros. What the deck really needed to be good, though, was a consistent turn-one play. The deck got this with Gnarled Scarhide, a 2 / 1 that can’t block. What’s especially good about this card, though, is its Bestow ability. This allows it to enchant a creature, giving it +2/+1, although it also takes away that creature’s ability to block. If the Enchanted creature dies, you still get to keep Scarhide on the battlefield as a creature again.
With Ragemonger on the board, you could actually play this guy for free. He’s a Minotaur that reduces Minotaur casting costs by RB. In casual play, Minotaurs are actually quite playable. As far as buylists are concerned, this is the only piece you will find that’s not bulk. You’re talking only a nickel (0.05 USD) for these guys in non-foil. For foils, though, you’re looking at $0.50 cash.
As someone who built a casual Minotaur deck for fun (they’re extremely cheap), I can say they are actually reasonably powerful. This is a must-have for that deck. With more Minotaurs being printed in Amonkhet, Minotaurs will probably become an even more popular deck to build.
One of my favorite cards from Journey into Nyx, the 0/5 Ram was actually quite popular in Standard for a time. Not only could he block well for just 1W, but he is an Enchantment creature, which made him very good in Constellation decks. He also gains you 1 life at the beginning of each of your upkeeps. He’s a lot of value on one card.
Outside of the occasional copies included in Modern Doran the Siege Tower/Assault Formation lists, you don’t see the Ram played much anymore. In those decks, though, the Ram can attack for 5. That’s pretty powerful. Assault Formation decks aside, this is a card casual players eat up. Considering the Ram’s competitive pedigree, that’s not at all surprising. While most buylists only pay about 0.10 USD for this uncommon, some buylists will pay more. It’s one of the more valuable cards on this list. Foils are especially valuable, buylisting for $2 or more!
Another Theros block card that was good in Standard, Searing Blood was pretty good in Burn decks in Modern for a time, too. Buylists used to pay as much as $0.25 for this card, but it's more like a nickel now for non-foil copies. But because it sees play in Modern, people have hoarded foil copies. Buylists will often pay $1 for this card in foil, and sometimes considerably more if Burn is doing well in Modern at that time.
Searing Blaze, an older card that’s similar, does more work in Modern than this does, however. It’s probably best to just hold onto 4 copies of this card and see if it ever gets played again - or reprinted in a Standard-legal set.
Originally printed as a common in Lorwyn, Springleaf Drum is a powerhouse in Pauper on Magic Online. It’s also pretty good in Affinity in Modern, one of the top decks in the format. While the Lorwyn foils buylist for twice as much as Born of the Gods versions ($6 to $3), the non-foils each buylist for about 0.25 - 0.50 USD. This is probably the most valuable card on this list, as it will always see play somewhere. Casual and Commander players both like this card, too.
This enchantment is super popular among casual players, as lifegain is an extremely popular mechanic on kitchen tables. Turning that lifegain directly into +1/+1 counters on your best creature is very powerful. There’s even been a Modern combo deck with Spike Feeder, which can remove a +1/+1 counter from itself to gain 2 life. This means that Sunbond will give it 2 +1/+1 counters from the lifegain. So not only is it infinite lifegain, but it also gives you an infinitely big creature to swing with. Sunbond has also gained in popular in Karlov of the Ghost Council EDH decks, a very lifegain happy Commander.
Sunbond can net you a quarter (0.25 USD) on some buylists. Foils can even net you as much as $1 or more.
Later reprinted in Magic Origins, Titan's Strength is perhaps one of the best Red creature pump spells ever printed. Not only does it give a creature +3/+1 for only a single Red mana, but you also get to Scry 1. Being able to manipulate the top of your deck is like drawing half of a card, as experts say - since you can send an undesirable draw to the bottom of the deck. In aggro decks where you need to keep drawing gas, this is a very desirable attribute for a card.
Copies of Titan's Strength used to buylist for about 0.10. Were it not for the reprint, it would be more. This is the only common on the list, but it’s that good and was legal in Standard through October 2016. After leaving Standard, there hasn't been much buylist demand, but it's still worth picking these out. There are occasionally decks in Modern that will play it.
(While not worth much to most buylists anymore, you should also pull out any copies you find of Bile Blight and Drown in Sorrow, as these Black removal cards still see Modern play from time to time.)
If you were to buylist just 4 copies - a playset - of each of these cards, you’d probably net a few bucks. That’s not including foils or additional copies of each card. On top of the 0.08 - 0.10 USD you could net from any bulk rares you have from the sets, you could find yourself a decent amount of pocket money.