diff --git a/game/shop_item.gd b/game/shop_item.gd
new file mode 100644
index 0000000..de5aea8
--- /dev/null
+++ b/game/shop_item.gd
@@ -0,0 +1,31 @@
+extends Node
+class_name ShopItem
+
+
+## The name of the item to display in the shop.
+@export var title_text: String
+
+## The description of the item to display in the shop.
+@export var description_text: String
+
+## The cost of the item to display in the shop.
+@export var cost_text: String
+
+## The item type to collect to purchase the item.
+##
+## If null, counts the items' value.
+@export var cost_tag: StringPath
+
+## The quantity of items to collect to purchase the item.
+##
+## If cost_tag is null, counts the items' value.
+@export var cost_quantity: int
+
+## The shape that the ghost should use to determine if the item's placement is valid.
+##
+## Concave shapes might have problems interacting with the placeable area.
+@export var placement_shape: Shape2D
+
+
+## What to do when this item is purchased.
+signal on_purchase
diff --git a/interface/ghost/ghost.gd b/interface/ghost/ghost.gd
index edaa3fe..0b418ca 100644
--- a/interface/ghost/ghost.gd
+++ b/interface/ghost/ghost.gd
@@ -30,47 +30,25 @@ class_name Ghost
 ## The [Sprite2D] node previewing the scene.
 @onready var preview_sprite: Sprite2D = $PlacementShape/PreviewSprite
 
-## The collision mask of objects that should prevent this object's placement.
-@export_flags_2d_physics var collision_mask_prevent_placement: int
 
-## The collision mask of objects that should be deleted on this object's placement.
-@export_flags_2d_physics var collision_mask_delete_placement: int
-
-## The texture that the preview sprite should display. 
-@export var preview_texture: Texture2D:
-	get:
-		return preview_texture
-	set(value):
-		preview_texture = value
-		# Quick priority fix
-		if preview_sprite:
-			preview_sprite.texture = value
+var can_place: bool = false
 
 
 func _ready():
-	collision_mask = collision_mask_prevent_placement | collision_mask_delete_placement
-	preview_sprite.texture = preview_texture
-
-
-func _physics_process(_delta: float):
-	# Update collision
-	update_can_place()
-
-
-var can_place: bool:
-	get:
-		return can_place
-	set(value):
-		can_place = value
-		modulate = valid_color if value else invalid_color
+	# Initialize the Area's collision mask
+	collision_mask = overlap_checker.collision_mask | placeable_area_checker.collision_mask | overlap_freer.collision_mask
 
 
 ## Update the value of [can_place].
-# DIRTY HACK: Relies on the placeable area being perfectly surrounded by solid bodies.
-func update_can_place() -> void:
+func update_state():
+	# DIRTY HACK: Relies on the placeable area being perfectly surrounded by solid bodies.
 	can_place = overlap_checker.is_overlapping_with == null and placeable_area_checker.is_overlapping_with != null
 
 
+func set_to_shop_item(si: ShopItem):
+	pass
+
+
 func materialize():
 	# Compatibility stub for Instantiator
 	if not can_place:
diff --git a/interface/ghost/ghost.tscn b/interface/ghost/ghost.tscn
index 2f074d8..b66079b 100644
--- a/interface/ghost/ghost.tscn
+++ b/interface/ghost/ghost.tscn
@@ -13,6 +13,8 @@ collision_layer = 0
 collision_mask = 4294967295
 input_pickable = false
 script = ExtResource("1_1bq64")
+valid_color = null
+invalid_color = null
 collision_mask_prevent_placement = 16
 collision_mask_delete_placement = 4
 
@@ -37,3 +39,4 @@ z_index = 10
 [connection signal="area_exited" from="." to="PlaceableAreaChecker" method="update_is_overlapping_with"]
 [connection signal="body_entered" from="." to="OverlapChecker" method="update_is_overlapping_with"]
 [connection signal="body_exited" from="." to="OverlapChecker" method="update_is_overlapping_with"]
+[connection signal="overlap_changing" from="OverlapChecker" to="." method="update_state"]
diff --git a/interface/ghost/placeable_area_checker.gd b/interface/ghost/placeable_area_checker.gd
index a51f387..f06d750 100644
--- a/interface/ghost/placeable_area_checker.gd
+++ b/interface/ghost/placeable_area_checker.gd
@@ -2,6 +2,12 @@ extends Node
 class_name PlaceableAreaChecker
 
 
+## Layers to consider when checking overlap with [PhysicBody2D].
+##
+## Ignored during the actual collision check, just used to expand it in the Ghost's initialization phase.
+@export_flags_2d_physics var overlap_mask: int
+
+
 ## The [Area2D] this script should act on.
 @onready var target: Area2D = get_parent()