Item List like Inventory

hey all,
I'm trying to make a Inventory system. For now I have:

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3. using System.Collections.Generic;
4.  
5.  
6. public class Inventory : MonoBehaviour {
7.     public int Gold;
8.     private Vector2 scrollPosition = Vector2.zero;
9.     static private ArrayList items = new ArrayList();
10.     static public bool Show = false;
11.  
12.  
13.    static public void AddNew(string name)
14.     {
15.      
16.         //Show = true;
17.         items.Add(name);
18.    
19.     }
20.    
21.     void OnGUI(){
22.         if(Show == true){
23.          scrollPosition = GUI.BeginScrollView(new Rect (10,10,200,270),scrollPosition, new Rect (0, 0, 200, 400));
24.          int b = 0;
25.          int i = 0;
26.     while(i < items.Count)
27.     {
28.         GUI.Button(new Rect(0,b,100,40),items[i].ToString());
29.         b +=50;
30.         i++;
31.        
32.     }
33.     GUI.EndScrollView();
34.     GUI.Label(new Rect(10,280,200,30),"Gold:" +Gold,"box");
35.         }
36.  
37.     }
38.     void Update(){
39.         if(Input.GetKeyUp("i")){
40.             if(!Show){
41.                 Show = true;
42.             }else if(Show){
43.                 Show = false;
44.             }
45.         }
46.     }
47. }
48.  

But now the while statement is called infinite when GUI is displayed. I know thats because OnGUI gets called every frame, but because of that there are more buttons of the same button/item. That's not what I want. So does someone know a other way to add a item and a button to the inventory without getting it duplicated(no loop in OnGUI)?