diff --git a/changelog.md b/changelog.md
index 3e760d8..6e3395e 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,7 @@
 # The Modding Tree changelog:
 
+- Amount is automatically supplied to buyable cost and effect functions.
+
 # v2.4.1 - 4/29/21
 - A number of minor fixes, many thanks to thepaperpilot.
 - The respec confirmation checkbox is now part of the respec-button component.
diff --git a/demo.html b/demo.html
index 1ec44e9..aa73dda 100644
--- a/demo.html
+++ b/demo.html
@@ -14,6 +14,8 @@
 	<script src="js/demo/demoLayers.js"></script>
 	<script src="js/demo/demoMod.js"></script>
 	<script src="js/technical/temp.js"></script>
+	<script src="js/technical/displays.js"></script>
+
 	<script src="js/game.js"></script>
 	<script src="js/utils.js"></script>
 	<script src="js/technical/systemComponents.js"></script>
diff --git a/docs/buyables.md b/docs/buyables.md
index 1a827bc..97c39de 100644
--- a/docs/buyables.md
+++ b/docs/buyables.md
@@ -32,9 +32,11 @@ Features:
 
 - title: **optional**. displayed at the top in a larger font. It can also be a function that returns updating text.
 
-- cost(): cost for buying the next buyable. Can have an optional argument "x" to calculate the cost of the x+1th object, but needs to use "current amount" as a default value for x. (x is a `Decimal`). Can return an object if there are multiple currencies.
+- cost(): cost for buying the next buyable. Can have an optional argument "x" to calculate the cost of the x+1th purchase. (x is a `Decimal`).
+    Can return an object if there are multiple currencies.
                     
-- effect(): **optional**. A function that calculates and returns the current values of bonuses of this buyable. Can return a value or an object containing multiple values.
+- effect(): **optional**. A function that calculates and returns the current values of bonuses of this buyable.  Can have an optional argument "x", similar to cost. 
+    Can return a value or an object containing multiple values.
 
 - display(): A function returning everything that should be displayed on the buyable after the title, likely including the description, amount bought, cost, and current effect. Can use basic HTML.
 
diff --git a/index.html b/index.html
index f95bb3d..89c9fc4 100644
--- a/index.html
+++ b/index.html
@@ -14,6 +14,7 @@
 	<script src="js/layers.js"></script>
 	<script src="js/mod.js"></script>
 	<script src="js/technical/temp.js"></script>
+	<script src="js/technical/displays.js"></script>
 	<script src="js/game.js"></script>
 	<script src="js/utils.js"></script>
 	<script src="js/technical/systemComponents.js"></script>
diff --git a/js/Demo/demoLayers.js b/js/Demo/demoLayers.js
index 4657669..b54d3d6 100644
--- a/js/Demo/demoLayers.js
+++ b/js/Demo/demoLayers.js
@@ -158,12 +158,12 @@ addLayer("c", {
             respecMessage: "Are you sure? Respeccing these doesn't accomplish much.",
             11: {
                 title: "Exhancers", // Optional, displayed at the top in a larger font
-                cost(x=player[this.layer].buyables[this.id]) { // cost for buying xth buyable, can be an object if there are multiple currencies
+                cost(x) { // cost for buying xth buyable, can be an object if there are multiple currencies
                     if (x.gte(25)) x = x.pow(2).div(25)
                     let cost = Decimal.pow(2, x.pow(1.5))
                     return cost.floor()
                 },
-                effect(x=player[this.layer].buyables[this.id]) { // Effects of owning x of the items, x is a decimal
+                effect(x) { // Effects of owning x of the items, x is a decimal
                     let eff = {}
                     if (x.gte(0)) eff.first = Decimal.pow(25, x.pow(1.1))
                     else eff.first = Decimal.pow(1/25, x.times(-1).pow(1.1))
diff --git a/js/technical/displays.js b/js/technical/displays.js
new file mode 100644
index 0000000..e69de29
diff --git a/js/technical/temp.js b/js/technical/temp.js
index 9b83527..c1bb302 100644
--- a/js/technical/temp.js
+++ b/js/technical/temp.js
@@ -7,7 +7,7 @@ var NaNalert = false;
 var activeFunctions = [
 	"startData", "onPrestige", "doReset", "update", "automate",
 	"buy", "buyMax", "respec", "onComplete", "onPurchase", "onPress", "onClick", "masterButtonPress",
-	"sellOne", "sellAll", "pay",
+	"sellOne", "sellAll", "pay", "actualCostFunction", "actualEffectFunction",
 ]
 
 var noCall = doNotCallTheseFunctionsEveryTick
@@ -36,6 +36,7 @@ function setupTemp() {
 		tmp[layer].prestigeButtonText = {}
 		tmp[layer].computedNodeStyle = []
 		setupBarStyles(layer)
+		setupBuyables(layer)
 	}
 	temp = tmp
 }
@@ -229,4 +230,22 @@ function setupBarStyles(layer){
 		bar.dims = {}
 		bar.fillDims = {}
 	}
+}
+
+function setupBuyables(layer) {
+	for (id in layers[layer].buyables) {
+		if (!isNaN(id)) {
+			let b = layers[layer].buyables[id]
+			b.actualCostFunction = b.cost
+			b.cost = function(x) {
+				x = x ?? player[this.layer].buyables[this.id]
+				return layers[this.layer].buyables[this.id].actualCostFunction(x)
+			}
+			b.actualEffectFunction = b.effect
+			b.effect = function(x) {
+				x = x ?? player[this.layer].buyables[this.id]
+				return layers[this.layer].buyables[this.id].actualEffectFunction(x)
+			}
+		}
+	}
 }
\ No newline at end of file