"Price ratio" is the unmodified number for calculating the cost of the next thing in a series (buildings, space items, time upgrades, etc). You'll find it listed on the Buildings and Space pages (and probably many other places).
To use this, you multiply the current cost * the price ratio and that's what the next building will cost.
For example:
The price ratio is modified by a bunch of things; here's a few common ones, but there are many more:
| Upgrade | Reduction | Notes |
|---|---|---|
| Enlightenment | -0.01 | Affects all structures |
| Golden Ratio | -(1 + Math.sqrt(5)) / 200 ~= 0.01618 | Affects all structures |
| Divine Proportion | -16 / 900 ~= -0.0177777778 | Affects all structures |
| Vitruvian Feline | -0.02 | Affects all structures |
| Renaissance | -0.0225 | Affects all structures |
| Ironwood Huts | -0.50 | Affects only Huts |
| Concrete Huts | -0.30 | Affects only Huts |
| Unobtainium Huts | -0.25 | Affects only Huts |
| Eludium Huts | -0.10 | Affects only Huts |
This changes the calculation to something like this: current cost * (price ratio - metaphysics modifiers - building modifiers).
So in the example above, if you had all the metaphysics upgrades, this is what the calculation would look like:
NOTE: The metaphysics modifiers (Enlightenment, Golden Ratio, Divine Proportion, Vitruvian Feline and Renaissance) apply only to structures in the Bonfire tab. They don't apply to Space structures. In other words, the price ratios listed on the Buildings page do receive metaphysics modifiers; the price ratios listed on the Space page don't recieve metaphysics modifiers.
Okay, okay, we all know why we're here. This is the answer according to WolframAlpha.
But here's the table to save you some time. This assumes you have all the metaphysics upgrades.
| Chronosphere | Unobtainium | Total cost |
|---|---|---|
| 1 | 2500 | 2500 |
| 2 | 2909 | 5409 |
| 3 | 3385 | 8793 |
| 4 | 3938 | 12.73K |
| 5 | 4582 | 17.31K |
| 6 | 5332 | 22.64K |
| 7 | 6203 | 28.84K |
| 8 | 7218 | 36.06K |
| 9 | 8398 | 44.46K |
| 10 | 9772 | 54.23K |
| 11 | 11.37K | 65.60K |
| 12 | 13.22K | 78.82K |
| 13 | 15.39K | 94.21K |
| 14 | 17.91K | 112.12K |
| 15 | 20.83K | 132.95K |
| 16 | 24.24K | 157.19K |
| 17 | 28.21K | 185.40K |
| 18 | 32.82K | 218.22K |
| 19 | 38.19K | 256.41K |
| 20 | 44.44K | 300.85K |
| 21 | 51.71K | 352.56K |
| 22 | 60.16K | 412.72K |
| 23 | 70.00K | 482.72K |
| 24 | 81.45K | 564.17K |
| 25 | 94.77K | 658.94K |
| 26 | 110.27K | 769.21K |
| 27 | 128.31K | 897.52K |
| 28 | 149.29K | 1.04M |
| 29 | 173.71K | 1.22M |
| 30 | 202.12K | 1.42M |
| 31 | 235.18K | 1.65M |
| 32 | 273.64K | 1.93M |
| 33 | 318.39K | 2.24M |
| 34 | 370.46K | 2.62M |
| 35 | 431.05K | 3.05M |
| 36 | 501.54K | 3.55M |
| 37 | 583.57K | 4.13M |
| 38 | 679.00K | 4.81M |
| 39 | 790.05K | 5.60M |
| 40 | 919.26K | 6.52M |
| 41 | 1.06M | 7.58M |
| 42 | 1.24M | 8.82M |
| 43 | 1.44M | 10.26M |
| 44 | 1.68M | 11.94M |
| 45 | 1.96M | 13.90M |
| 46 | 2.28M | 16.18M |
| 47 | 2.65M | 18.83M |
| 48 | 3.08M | 21.91M |
| 49 | 3.59M | 25.50M |
| 50 | 4.18M | 29.68M |
| 51 | 4.86M | 34.54M |
| 52 | 5.66M | 40.20M |
| 53 | 6.58M | 46.78M |
| 54 | 7.66M | 54.44M |
| 55 | 8.91M | 63.35M |
| 56 | 10.37M | 73.72M |
| 57 | 12.07M | 85.79M |
| 58 | 14.04M | 99.83M |
| 59 | 16.34M | 116.17M |
| 60 | 19.01M | 135.18M |
| 61 | 22.12M | 157.30M |
| 62 | 25.74M | 183.04M |
| 63 | 29.95M | 212.99M |
| 64 | 34.85M | 247.84M |
| 65 | 40.54M | 288.38M |
| 66 | 47.18M | 335.56M |
| 67 | 54.89M | 390.45M |
| 68 | 63.87M | 454.32M |
| 69 | 74.32M | 528.64M |
| 70 | 86.47M | 615.11M |
| 71 | 100.61M | 715.72M |
| 72 | 117.07M | 832.79M |
| 73 | 136.22M | 969.01M |
| 74 | 158.49M | 1.12G |
| 75 | 184.42M | 1.31G |
| 76 | 214.58M | 1.52G |
| 77 | 249.67M | 1.77G |
| 78 | 290.50M | 2.06G |
| 79 | 338.01M | 2.40G |
| 80 | 393.29M | 2.79G |
| 81 | 457.61M | 3.25G |
| 82 | 532.45M | 3.78G |
| 83 | 619.53M | 4.40G |
| 84 | 720.85M | 5.12G |
| 85 | 838.74M | 5.96G |
| 86 | 975.91M | 6.94G |
| 87 | 1.13G | 8.07G |
| 88 | 1.32G | 9.39G |
| 89 | 1.53G | 10.92G |
| 90 | 1.78G | 12.70G |
| 91 | 2.08G | 14.78G |
| 92 | 2.42G | 17.20G |
| 93 | 2.81G | 20.01G |
| 94 | 3.27G | 23.28G |
| 95 | 3.81G | 27.09G |
| 96 | 4.43G | 31.52G |
| 97 | 5.16G | 36.68G |
| 98 | 6.00G | 42.68G |
| 99 | 6.99G | 49.67G |
| 100 | 8.13G | 57.80G |