Damage divided by the price pill
For dinos, DMG on the orange pill divided by the green price. Ankylosaurus is 140 / 92. Pachycephalosaurus is 30 / 30. That is the whole formula. No hidden multiplier.
S and A are index cards with the best damage per dollar you can read off the pills. Shop rows are ranked by the sentence on that restock, not by a made-up meta.
Updated
For dinos, DMG on the orange pill divided by the green price. Ankylosaurus is 140 / 92. Pachycephalosaurus is 30 / 30. That is the whole formula. No hidden multiplier.
Bone Mender, Tar Pit, and the rest come from one timed restock. They are ranked by what the row says it does, and a later restock can remove them.
DMG 140 for $92, about 1.52 damage per dollar. Best ratio on the 33 dinos. SPD is only 11, so it is not the fast card.
DMG 30 for $30. Best ratio you can buy before Ankylosaurus exists. HP 140, SPD 20.
SPD 30, the fastest pill on the index, for $320. DMG 95 and HP 1.4K. Buy it when the rest of the board is slow.
Thick tar. Anything crossing it crawls. $180000, x1 Stock, Legendary, on the restock we filmed. Cheapest of those three traps.
First red boss card. HP 6K, DMG 90, SPD 3.5, $900. The fight to know, not a cheap damage buy.
Repairs your most damaged defences. $17500, x1 Stock, Epic. Useful only while that row is actually in the shop.
HP 380, but DMG 15 for $55. A tank pill, a weak damage-per-dollar pill. Buy it for the red number.
Rebuilds destroyed traps mid-run. $300000. Last of the three, and only after a trap exists to rebuild.
5.7% on the hatch panel, about 1 in 18, with no pity line. Not an index card and not a wave unlock.
If a patch changes Ankylosaurus's DMG or price, this order changes with it. The shop half of the list was already temporary on the day it was filmed, because the header said new items were coming.
FAQ
It is the right first buy at $6, and SPD 26 is excellent, but DMG 4 for $6 is a worse ratio than Pachycephalosaurus or Ankylosaurus. First buy and best ratio are different questions.
No. Grovebreaker has HP 30K and costs $4,000 for DMG 120. That is a wave you have to clear, not a good damage-per-dollar purchase. Titanhorn is listed because it is the first boss, and the note says so.