subtract rupees when buying magic bean

Sprites/NPCs/bean_vendor.asm

@@ -122,6 +122,19 @@ Sprite_BeanVendor_Main:
   {
     %PlayAnimation(0,0,1)
 
+    REP #$20
+    LDA.l $7EF360
+    CMP.w #$64 ; 100 rupees
+    SEP #$30
+    BCC .not_enough_rupees
+
+      REP #$20
+      LDA.l $7EF360
+      SEC
+      SBC.w #$64 ; Subtract 100 rupees
+      STA.l $7EF360
+      SEP #$30
+
       LDA.b #$07 
       JSL Sprite_SpawnDynamically
       LDA.b #$02 : STA.w SprAction, Y
@@ -130,16 +143,19 @@ Sprite_BeanVendor_Main:
       LDA.w SprYH, X : STA $03
       LDA.w SprXH, X : STA $01
       ; TODO: Set a flag that says you've got the magic bean
-    %ShowUnconditionalMessage($144)
+      %ShowUnconditionalMessage($145)
       %GotoAction(0)
       RTS
+    .not_enough_rupees
+    %GotoAction(4)
+    RTS
   }
 
   ; 0x04 - Player Said No
   PlayerSaidNo:
   {
     %PlayAnimation(0,0,1)
-    %ShowUnconditionalMessage($145)
+    %ShowUnconditionalMessage($144)
     %GotoAction(0)
     RTS
   }