Zendikar was one of the most popular sets of all time, and the Zendikar block was equally well-received, causing a massive increase in the player base. Brian DeMars wrote a nice retrospective article on the first Zendikar set that you can read here. The block featured a number of powerful cards that have had lasting impacts on constructed formats including Jace, the Mind Sculptor, Emrakul, the Aeons Torn, Kozilek, Butcher of Truth, Ulamog, the Infinite Gyre, Stoneforge Mystic, and the first printing of the enemy fetch lands. In additon to these powerful rares and mythics, It also has a number of uncommons worth noting.
We got an upgraded version of Hedron Crab in Battle for Zendikar with Ruin Crab, but the original crab still commands almost $8. I have previously mentioned how Mill players are a devoted group, and this price is one of the best pieces of evidence. On a side note, I definitely expect Ruin Crab to be the most valuable uncommon from BFZ, though I imagine the print run is much higher now so the price ceiling is lower.
Trailblazer's Boots essentially makes commanders unblockable thanks to the plethora of non-basics played in Commander.
Watchlist - Zendikar
While Punishing Fire has been reprinted twice, those reprints were the original Commander product in 2013 and Duel Decks: Knights vs Dragons. This card spiked hard a few years ago when people figured out the combo with Grove of the Burnwillows. This combo was so oppressive against creature-based decks that Punishing Fire was banned in Modern, where it remains. Should it ever get unbanned, this is easily a $5+ uncommon.
Ravenous Trap Is one of the few cards upgraded to rare when reprinted. after Zendikar, it appeared in Double Masters and Mystery Booster, and those reprints likely didn't add much to the supply. The current price is low mostly due to the greatly reduced power level of the Modern Izzet Phoenix decks following the banning of Faithless Looting, of which Ravenous Trap was a premium hate card. While we may not see Faithless Looting ever get unbanned in Modern, it is only a matter of time for another graveyard-centric deck to rise to power and dominate the format and when it does this will be an obvious sideboard inclusion. Get your copies now, while they are basically bulk.
Seedborn Muse is a must kill target in Commander, so it isn't surprising that this uncommon with a similar effect is valuable. Quest for Renewal is the only uncommon from the set that reaches our greater than $1.49 criteria. It is also important to remember that the draft format at the time was Zendikar, Zendikar, Worldwake. When Rise of the Eldrazi came out it was drafted as a single set, thus a lot less Worldwake was opened than either Zendikar or Rise of the Eldrazi.
Watchlist - Worldwake
While good ol' Tec Edge has taken a back seat to Field of Ruin or Ghost Quarter as the preferred land that destroys lands in Modern, it is important to note that unlike the other two, Tectonic Edge does NOT give your opponent a basic land, which most decks now run.
Rise of the Eldrazi
Inquisition of Kozilek is one of the premier hand disruption spells in Modern. While it does have some restrictions, the fact that the majority of cards in modern have a Mana Value of three or less means that it hits almost everything that is relevant. While inferior to Thoughtseize in terms of selection, in a format where the best dual lands can cost you two life to come into play untapped, the two life lost casting Thoughtseize matters.
This is one of the few good level up cards, as getting Joraga Treespeaker to the first level is essentially free. The level up mechanic overall was a pretty big miss from a practical standpoint, falling so flat it is unlikely to be brought back in a premiere product. This means Joraga Treespeaker is unlikely to be reprinted.
Annihilator proved to be an incredibly powerful mechanic and when stapled onto creatures made them far more competitive. In addition to its first printing, Pathrazer of Ulamog has only a WPN promo and a Mystery Booster printing. Demand for this is likely heavily influenced by those who don't want to spend the money on the original big Eldrazi but still want creatures with Annihilator. Given its size and the requirement of three blockers, it tends to be a six-for-one when attacking: three sacrificed from the annihilator triggers and three creatures to block it.
This is one of my friend's pet cards. He was the first person I saw actually include it in a Commander deck years ago. Not of This World is a free counterspell to protect a commander with high power, or to protect any permanent if you are willing to pay the seven mana. It is a tribal spell, which can be relevant at times. It was recently reprinted in the Mystery Booster product, which is likely an insignificant print run to affect the price.
Wall of Omens is another modern staple that has been printed into oblivion, crushing its price the past few years.
Watchlist - Rise of the Eldrazi
This is definitely a hidden gem from Rise of the Eldrazi. While it has been reprinted once in the original Commander product, this is a card that both ramps you and can create large numbers of tokens repeatedly. Foils are still relatively cheap at under $3.
I would have had a lot more hope for this card breaking out if it hadn't been included in Commander Legends. Interest in that set has seemed to wane in the past few months though, so depending on if a lot more of that product gets opened or not, Pennon Blade is still a card to watch. You can pick up foils of the Rise of the Eldrazi version for around $1, which seems like the better option to take if you are going to speculate on this card.